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TPO31 Reading
Passage 1
Speciation in Geographically Isolated Populations
Paragraph 1
Evolutionary biologists believe that speciation, the formation of a new species, often begins when some kind of physical barrier arises and divides a population of a single species into separate subpopulations. Physical separation between subpopulations promotes the formation of new species because once the members of one subpopulation can no longer mate with members of another subpopulation, they cannot exchange variant genes that arise in one of the subpopulations. In the absence of gene flow between the subpopulations, genetic differences between the groups begin to accumulate. Eventually the subpopulations become so genetically distinct that they cannot interbreed even if the physical barriers between them were removed. At this point the subpopulations have evolved into distinct species. This route to speciation is known as allopatry (“allo‐” means “different”, and “patria” means “homeland”).
Q1 The word ”promotes” in the passage is closest in meaning to
A. Describes
B. Encourages
C. delays
D. requires
正确答案:B 解析:promote 本身是促进的 意思。另外原文这个句子意思 是 subpopulations 间的物理分 割...了新物种的形成,A 描 述,B促使,C减弱,D要求。 所以 B 最合适的。
Q2 According to paragraph 1, allopatric speciation involves which of the following?
A. The division of a population into subspecies
B. The reuniting of separated populations after they have become distinct species
C. The movement of a population to a new homeland
D. The absence of gene flow between subpopulations
正确答案:D
解析:根据 allopatric 进行定位,可定位至本段的最后一句。最后一句是对前面现象的一个命名和定义。也就是前面的内容，就是allopatry的意思。A与原文不符，原文是物理barrier把population分割成subpopulation。B不对，对应eventually这句。C没提到。D正确，对应从in the absence到最后。
Paragraph 2
Allopatric speciation may be the main speciation route. This should not be surprising, since allopatry is pretty common. In general, the subpopulations of most species are separated from each other by some measurable distance. So even under normal situations the gene flow among the subpopulations is more of an intermittent trickle than a steady stream. In addition, barriers can rapidly arise and shut off the trickle. For example, in the 1800s a monstrous earthquake changed the course of the America. The change separated populations of insects now living along opposite shore, completely cutting off gene flow between them.
?Q3 Why does the author provide the information that “the subpopulations of most species are separated from each other by some measurable distance”?
A. To indicate how scientists are able to determine whether subpopulations of a species are are allopatric
B. To define what it means for a group of animals or plants to be a subpopulation
C. To suggest that allopatric speciation is not the only route to speciation
D. To help explain why allopatric speciation is a common way for new species to come about
正确答案:D 解析:高亮句前面的一句话, 也就是本段的第一句(主旨 句),allopatry 是 main speciation route。本段都是围 绕着这个主题来进行的。所以 选择D
Q4 The word ”accumulate” in the passage is closest in meaning to
A. Become more significant
B. Occur randomly
C. Gradually increase in number
正确答案:C 解析:词汇所在句说群落间基 因的区别开始 accumulate。 Eventually 对理解这个词很有 帮助。怎么怎么样了,最终达 到了后面这句的效果。那么也 就是说是渐渐发展的,才能说 最终。所以答案在 A,C 之间。 但因为这里强调了缓慢的过 程,gradually 更合适。
Q5 In paragraph 2, why does the author mention that some insect populations were ?separated from each other by a change in the ?course of Mississippi River caused by an earthquake?
A. To make the point that some kind of physical barrier separates the subpopulations of most species
B. To support the claim that the condition of allopatry can sometimes arise in a short time
C. To provide an example of a situation in which gene flow among the subpopulations of a species happens at a slow rate
D. To explain why insects living along opposite shores of the Mississippi River are very different from each other
?
正确答案:B 解析:For example 后面就是 题目中的内容,那么也就是说 作者用此作为例子来支持前 面的观点。而前面的观点是 barriers 也有可能突然发生, 然后截断了这种 trickle。所以 对应的是 B
Paragraph 3
Geographic isolation also can proceed slowly, over great spans of time. We find evidence of such extended events in the fossil record, which affords glimpses into the breakup of formerly continuous environments. For example, during past ice ages, glaciers advanced down through North America and Europe and gradually cut off parts of populations from one another. When the glaciers retreated, the separated populations of plants and animals came into contact again. Some groups that had descended from the same parent population were no longer reproductively compatible— they had evolved into separate species. In other groups, however, genetic divergences had not proceeded so far, and the descendants could still interbreed— for them, reproductive isolation was not completed, and so speciation had not.
Paragraph 4
Allopatric speciation can also be brought by the imperceptibly slow but colossal movements of the tectonic plates that make up Earth’s surface. About 5 million years ago such geologic movements created the land bridge between North America and South America that we call the Isthmus of Panama. While previously the gap between the continents had allowed a free flow of water, now the isthmus presented a barrier that divided the Atlantic Ocean from the Pacific Ocean. This division set the stage for allopatric speciation among populations of fishes and other marine species.
Q7 The word ”colossal” in the passage is occurred.
closest in meaning to
A. consistent
B. gradual
C. enormous
D. effective
正确答案:C 解析:Colossal 本身是巨大的, 非常的意思,这里对应 C 选 项。分析原文也可以得到正确 答案,与 colossal 并列的词汇 是 slow,中间的逻辑关系词 是 but,证明两者有转折关系。 再经过推断,缓慢的过程但量 大的话就足以发生巨大的改 变。所以选 C
Q8 According to paragraph 4, which of the following is true of the geologic movements ??that brought about the Isthmus of Panama?
A. The movements brought populations of certain fishes and marine organisms into contact with one another for the first time.
B. The movements transferred populations of fishes and other marine animals between the Pacific and Atlantic Oceans.
C. The movement created conditions that allowed water to flow more freely between the Pacific and Atlantic Oceans.
D. The movement created conditions for the formation of new species of fishes and other marine animals.
正确答案:D 解析:根据 Isthmus of Panama 定位。从 About 开始。本段的 最后一句说了 isthmus of Panama 带来的结果,对应了 D 选项。
Paragraph 5
In the 1980s, John Graves studied two populations of closely related fishes, one population from the Atlantic side of isthmus, the other from the Pacific side. He compared four enzymes found in the muscles of each population. Graves found that all four Pacific enzymes function better at lower temperatures than the four Atlantic versions of the same enzymes. This is significant because Pacific seawater is typically 2 to 3 degrees cooler than seawater on the Atlantic side of isthmus. Analysis by gel electrophoresis revealed slight differences in amino acid sequence of the enzymes of two of the four pairs. This is significant because the amino acid sequence of an enzyme is determined by genes.
Q9 The word ”sequence” in the passage is closest in meaning to
A. quality
B. order
C. function
D. number
正确答案:B 高亮词所在句提到了氨基酸 啊,酶啊,pairs 啊什么的, 其实就是在说成对的基因呀, 胶体电泳分析揭示了少量的 氨基酸...的不同。A 质量,C 功能,D 数量都不对,应该选 择 B 顺序。(了解一点生物相 关知识就很容易明白啦)而且 sequence本身也是序列,顺序 的意思。
Q10 According to paragraph 5, by comparing? the enzymes from two related groups of fishes on opposite sides of the isthmus, Graves found evidence that
A. there were slight genetic divergences between the two groups
B. the Atlantic group of fishes were descended from the Pacific group of fishes
C. the temperature of water on either side of the isthmus had changed
D. genetic changes in the Atlantic group of fishes were more rapid and frequent than
正确答案: A
解析: 跟上面一题对应的位置是一 样的。或者可以根据 Graves found 定位,阅读后面的部分 可以很容易得出答案 A。
Paragraph 6
First, at least some of the observed differences between the enzymes of the Atlantic and Pacific fish populations were not random but were the result of evolutionary adaptation. Second, it appears that closely related populations of fishes on both sides of the A isthmus are starting to genetically diverge from each other. Because ?Graves’s study of geographically isolated ?populations of isthmus fishes offers a glimpse of the beginning of a process of are neutral or adaptive, divergences here ?might be evidence of allopatric speciation in process.
Q11 It can be inferred from paragraph 5 and 6 that the reason Graves concluded that some of the differences between the Pacific and Atlantic enzymes were not random was that
A. each of the Pacific enzymes works better in cooler waters
B. the Enzymes of the Atlantic fish populations had not changed since the formation of the Isthmus of Panama
C. gel electrophoresis showed that the changes benefited both the Atlantic and the Pacific fish populations
D. the differences between the enzymes disappeared when the two fish populations were experimentally switched to other side of the isthmus
正确答案:
解析:A 对应了第五段红色标 注句子,B 明显错误,文章一 直在说改变。
C 文章提到 gel electrophoresis 的地方只是说氨基酸的顺序 改变了,但没说 both benefited。D 文章也没提到。
Q12 Which of the sentence below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. Graves’s study provides evidence that isthmus fishes are in the process of becoming geographically isolated.
B. Graves’s study of mutating isthmus fishes yields results that differ from results of other studies involving allopatric speciation.
C. Graves’s study of isolated populations of isthmus fishes provides some evidence that allopatric speciation might be beginning.
D. Graves’s study indicates that when isolated, populations of isthmus fishes register neutral or adaptive mutations.
正确答案: C 解析:原文高亮句翻译为:格 雷夫斯关于地峡鱼类地域隔 离的种群研究为中性或适应 性突变的逐渐累积过程的开 始提供了一些线索,这里的差 异可能会给正在进行的异域 性物种的形成提供证据。所以 主干部分为...的研究为..的开 始提供了线索。对应 C。
Paragraph 4
Allopatric speciation can also be brought by the imperceptibly slow but colossal movements of the tectonic plates that make up Earth’s surface. About 5 million years ago such geologic movements created the land bridge between North America and South America that we call the Isthmus of Panama. While previously the gap between the continents had allowed a free flow of water, now the isthmus presented a barrier that divided the Atlantic Ocean from the Pacific Ocean. This division set the stage for allopatric speciation among populations of fishes and other marine species.
Q13 Look at the four squares [] that indicate where the following sentence could be added to the passage.
The formation of the isthmus had important consequences for global patterns of ocean water flow.
Where would the sentence best fit? Click on a square to add the sentence to the passage.
正确答案: B 解析:要插入的句子提到了 formation of the isthmus,那么 证明句子前面的内容中已经 出现了 isthmus,而后面则是 要说明 consequences。第二个 空符合逻辑,所以选择 B
Q14 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
?
Allopatric speciation takes place when physically separated populations of a single species gradually diverge genetically to the point of becoming unable to interbreed.
Answer choices
A. Allopatric speciation is common because the gene flow between subpopulations is generally limited and the barriers that completely separate subpopulations can arise in a variety of ways.
B. During past ice ages, some, but not all, subpopulations separated by glaciers evolved into distinct species.
C. Speciation does not need to take place through allopatry because subpopulations will form distinct species whenever there are adaptive advantages to not interbreeding with other subpopulations.
D. Physical barriers from glaciers and the movement of tectonic plates form so slowly that the subpopulations on either side of the barriers usually do not form distinct species.
E. Graves’s study of fish populations separated by the Isthmus of Panama may well provide a picture of the beginning stages of speciation.
F. Graves’s study of physically separated fish populations show that there must be large differences between the ?environments of the isolated populations if allopatric speciation is to take place.
正确答案: ABE
A对应文章第 二段。
B对应文章第 三段
C错误,与文 章多处矛盾,文章一直在强调 allopatry 是最主要的 speciation route。
D错误,对应 文章第三段,可参考词汇题 colossal 的分析,文章中不仅 提到了 Slow 也说到的大量, 从而导致了 distinct species。
E与 12 题的 对应位置一样。
F错误,与文 章中词汇题 sequence 所再句 矛盾,那一句提到了 slight difference。
Passage 2
Early Childhood Education
Paragraph 1
Preschools‐‐educational programs for children under the age of five‐‐differ significantly from one country to another according to the views that different societies hold regarding the purpose of early childhood education. For instance, in a cross‐country comparison of preschools in China, Japan, and the United States, researchers found that parents in the three countries view the purpose of preschools very differently. Whereas parents in China tend to see preschools primarily as a way of giving children a good start academically, Japanese parents view them primarily as a way of giving children the opportunity to be members of a group. In the United States, in comparison, parents regard the primary purpose of preschools as making children more independent and self‐reliant, although obtaining a good academic start and having group experience are also important.
Q1 According to paragraph 1, parents in Japan tend to think of preschool primarily as a place where children can
?A. get a good academic start
B. expand their emotional development
C. become more independent
D. experience being part of a group
正确答案:D 解析:根据题目中 Parents in Japan,定位至文章红色标注 句(Japanese parents....,)可 直接得到答案 D
?Q2 The word "Whereas" in the passage is closest in meaning to
A. Although
B. Because
C. Moreover
D. Already
正确答案:A 解析:这里轻微对比了 China 和 Japanese 家长之间的差别, 所以 A 最合适。
Paragraph 2
While many programs designed for preschoolers focus? primarily on social and emotional factors, some are geared mainly toward promoting cognitive gains and preparing preschoolers for the formal instruction they will experience when they start kindergarten. In the United States, the best‐known program designed to promote future academic success is Head Start. Established in the 1960s when the United States declared the War on Poverty, the program has served over 13 million children and their families. The program, which stresses parental involvement, was designed to serve the "whole child", including children's physical health, self‐confidence, social responsibility, and social and emotional development.
Q3 The word "focus" in the passage is closest
??? A. consider
B. respect
C. concentrate
D. advise
正确答案:C 解析:Focus 是集中的意思, 另外这里和 focus 配合的介词 是 on, concentrate 也用 on, 所以这里帮助推断。
Q4 It can be inferred from paragraph 2 that the Head Start program was designed to serve ??children who
A. come from families that do not have a lot of money
B. are not doing very well in kindergarten
C. were born in the 1950s
D. need programs that focus primarily on social and emotional factors
正确答案:A 解析:根据 Head Start 定位, 后面的内容就是对 Head Start 这个program的介绍,首先是 1960 年开始的,和 C 矛盾, 然后说是在US宣布了War on Poverty(贫穷)的时候,所 以是为穷人设计的,符合 A。 B 没提到,D 在这段的开头提 到了,但是不是针对 Head Start 的描述,Head Start 目标 是“whole child”,德智体美 劳全面发展。
Paragraph 3
Whether Head Start is seen as successful or not depends on the lens through which one is looking. If, for instance, the program is expected to provide long‐term increases in IQ (intelligence quotient) scores, it is a disappointment. Although graduates of Head Start programs tend to show immediate IQ gains, these increases do lot last. On the other hand, it is clear that Head Start is meeting its goal of getting preschoolers ready for school. Preschoolers who participate in Head Start are better prepared for future schooling than those who do not. Furthermore, graduates of Head Start programs have better future school grade. Finally, some research suggests that ultimately Head Start graduates show higher academic performance at the end of high school, although the gains are modest.
Q5 According to paragraph 3, the Head Start ?program had the following?
A. Helping children adjust to school
B. Providing long‐term increase in IQ scores
C. Improving school performance throughout high school
D. Preventing children from being placed in special‐education classes
正确答案:B 解析:B 对应红色标注部分。 其他的几个选项根据后文中 的内容都是正确的。
Paragraph 4
In addition, results from other types of preschool readiness programs indicate that those who participate and graduate are less like to repeat grades, and they are more like to complete school than readiness program, for every dollar spent on the program, taxpayers saved seven dollars by the time the graduates reached the age of 27.
Q6 In paragraph 4, the author mentions the ?"results from other types of readiness ??programs" to
A. provide support for the idea that preschool readiness programs have been somewhat successful
B. question the idea that Head Start is more effective than other preschool readiness programs
C. indicate school completion is usually the most reliable indicator of success in most readiness programs
D. emphasize that participation in readiness programs can be increased if costs are reduced
正确答案A。解析：利用results of readiness program定位到本段第一句，本句内容说，参加这些?program 留级的可能性小,而 且还能省钱。所以选 A。
Q7 According to paragraph 4, a cost‐benefit ?analysis of one preschool readiness program revealed that
A. only one dollar's worth of benefit was gained for every seven dollars spent on the program
B. the benefits of the program lasted only until the participants reached age 27
C. taxpayers saved seven dollars for every dollar spent on the program
D. to be successful, the program would need to receive about seven times as much money as it currently receives
正确答案:C 解析:对饮文章第四段中标注 的红色句子。A 改变了原文意 思,B 文章没说只道 27,D 和原文意思正好相反。
Paragraph 5
The most recent comprehensive evaluation of early intervention programs suggests that, taken as a group, preschool programs can provide significant benefits, and that government funds invested early in life may ultimately lead to a reduction in future costs. For instance, compared with children who did not participate in early intervention programs, participants in various programs showed gains in emotional or cognitive development, better educational outcomes, increased economic self‐sufficiency, reduced levels of criminal activity, and improved health‐related behaviors. Of course, not every program produced all these benefits, and not every child benefited to the same extent, Furthermore, some researchers argue that less‐expensive programs are just as good as relatively expensive ones, such as Head Start. Still, the results of the evaluation were promising, suggesting that the potential benefits of early intervention can be substantial.
Q8 The word "comprehensive" in the passage ??is closest in meaning to
A. easily understood
B. thorough
C. respectable
D. objective
正确答案:B 解析:comprehensive 是全面 的,综合的意思。这里说 evaluation 说明。那么使用 代入法,A 最易懂的,B 完整 的,C 值得尊敬的,D 客观的 中,AC 可以排除,不通顺, B 和 D 之间就需要理解 comprehensive 的词意来确定 了。
Q9 Paragraph 5 mentions that participants in ?early intervention programs have been shown to do all of the following better than
? A. Take care of their health
B. Support themselves financially
C. Take care of their own children
D. Have increased emotional development
正确答案:C 解析:根据关键词定位至 For instance 开始的内容。红色标 注部分都是参加不参加好的 地方,其中不包括 C
Q10 According to paragraph 5, which of the following is true about the benefits of early ??intervention programs?
A. These programs produce good short‐term benefits but few long‐term benefits.
B. Only the most expensive programs provide substantial benefits.
C. The Head Start program provides a range of benefits that no other program can provide.
D. Some children benefit more than others do from these programs.
正确答案: D
A 对应“reduction in future costs”证明是 long term 的 benefit,所以 A 错误。B 对应 “less‐expensive programs are just as good as relatively expensive ones”说明便宜和 贵的一样好,B 选项也不对。 C 没提到。D 对应 not every child benefited to the same extent,正确。
Paragraph 6
Not everyone agrees that programs that seek to enhance academic skills during the preschool years are a good thing. In fact, according to developmental psychologist David Elkind, United States society tends to push children so rapidly that they begin to feel stress and pressure at a young age. Elkind argues that academic success is largely dependent upon factors out of parents' control, such as inherited abilities and a child's rate of maturation. Consequently, children of a particular age cannot be expected to master educational material without taking into account their current level of cognitive development. In short, children require development appropriate educational practice, which is education that is based on both typical development and the unique characteristics of a given child.
Q11 The word "seek" in the passage is closest in meaning to
A. claim
B. manage
C. fail
D. attempt
正确答案: D
解析:Seek 本身是寻找,追 求的意思。
A 是要求,B 是设法,管理, C 是失败,D 是尝试,所以 D 最合适。
Q12 The passage mentions "developmental psychologist David Elkind" in order to
A. give an example of an expert who has designed an effective early childhood education program
B. introduce an alternative view about the value of early childhood education
C. explain why early childhood education programs are less effective in the United States than in other countries
D. refute the claim that academic success is dependent on factors outside parents' control
正确答案: B 解析:关键词对应后,根据本 段的第一句,Elkind 是作为反 面观点的例子出现的,所以是 为了阐述另外一面的观点,选 B
Not everyone agrees that programs that seek to enhance academic skills during
the preschool years are a good thing. In fact, according to developmental psychologist David Elkind, United States society tends to push children so rapidly that they begin to feel stress and pressure at a young age. Elkind argues that academic success is largely dependent upon factors out of parents' control, such as inherited abilities and a child's rate of maturation. Consequently, children of a particular age cannot be expected to master educational material without taking into account their current level of cognitive development. In short, children require development appropriate educational practice, which is education that is based on both typical development and the unique characteristics of a given child.
Q13 Look at the four squares【】that indicate where the following sentence could be added the to the passage.
According to Elkind, not only does this cause the child emotional distress, it also fails to bring the intended cognitive gains.
Where would the sentence best fit? Click on a square to add the sentence to the passage.
正确答案B。解析:要插入的句子中有 not only, also 的结构,那么起到 的就是承上启下的作用。句子 前面一定出现过 emotional distress 的内容,后面要引出 的就是 intended cognitive gains 的相关内容。所以选 B
Q14 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Preschool programs provide opportunities for young children to develop emotionally, and cognitively.
A In addition to stressing academic development, preschools should be enjoyable, since studies show that children benefit from programs they find fun.
B Preschool programs such as Head Start have been shown to help prepare children for school and may also have long‐term benefits in helping children become effective adults
C Studies have shown that preschool programs are most effective when they focus on only one area of development rather than trying to serve the “whole child”.
D The primary purpose of preschool programs varies by country, with some stressing the importance of group experience, and others self‐reliance or getting a good academic start.
E Critics of preschool programs argue that these programs put undue pressure on ?children and may not be effective if children are not developmentally ready for academic work.
F David Elkind is a critic of publicly funded ?preschool programs, arguing that the children’s emotional development.
正确答案: BDE
A原文没提到。B对应原文第 4段。C跟原文矛 盾,whole children 是“head Start”的主要目标,而且文章 也一直在说这个 program 很 好。D对应原文第 一段,不同国家家长有不同的 观点。E对应文章最后一段。F对应原文最 后一段,但是文章并没有说 parent cannot control,而是说 这个是孩子能否成功的至关 重要的因素。
Passage 3
Savanna Formation
Paragraph 1
Located in tropical areas at low altitudes, savannas are stable ecosystems, some wet and some dry consisting of vast grasslands with scattered trees or shrubs. They occur on a wide range of soil types and in extremes of climate. There is no simple or single factor that determines if a given site will be a savanna, but some factors seem to play important roles in their formation.
Paragraph 2
Savannas typically experience a rather prolonged dry season. One theory behind savanna formation is that wet forest species are unable to withstand the dry season, and thus savanna, rather than rain forest, is favored on the site. Savannas experience an annual rainfall of between 1,000 and 2,000 millimeters, most of it falling in a five‐ to eight‐month wet season. Though plenty of rain may fall on a savanna during the year, for at least part of the year little does, creating the drought stress ultimately favoring grasses. Such conditions prevail throughout much of northern South America and Cuba, but many Central American savannas as well as coastal areas of Brazil and the island of Trinidad do not fit this pattern. In these areas, rainfall per month exceeds that in the above definition, so other factors must contribute to savanna formation.
Q1 The word "prolonged" in the passage is closest in meaning to
A. predictable
B. destructive
C. lengthy
D. unproductive
正确答案:C 解析:可以根据词根分析,原 文中 prolonged,词根为 long, 长度。Prolonged 为延长的。 选项中 C,length 本来是长度 的意思,lengthy 变为形容词 格式,符合原词词义。
?Q2 In paragraph 2, the author mentions ?savannas in Central America island of Trinidad in order to:
A. argue that these savannas are similar to those in South America and Cuba
B. point out exceptions to the pattern of savanna formation in areas with drought stress
C. provide additional examples of savannas in areas with five‐ to eight‐month wet seasons
D. indicate areas where savannas are being gradually replaced by rain forests
正确答案:B 解析:以 savannas in Central America, Brazil, and the island of Trinidad 作为关键词定位到 红色标注句,看到这半句和前 半句中间有 but 的转折,那么 也就是说 central amercia, brazil 这些地方和前面介绍的 不一样,所以是例外情况。
Paragraph 3
In many characteristics, savanna soils are similar to those of some rain forests, though more extreme. For example, savanna soils, like many rain forest soils, are typically oxisols (dominated by certain oxide minerals) and ultisols (soils containing no calcium carbonate), with a high acidity and notably low concentrations of such minerals as phosphorus, calcium, magnesium, and potassium, while aluminum levels are high. Some savannas occur on wet, waterlogged soils; others on dry, sandy, well‐drained soils. This may seem contradictory, but it only means that extreme soil conditions, either too wet or too dry for forests, are satisfactory for savannas. More moderate conditions support moist forests.
Q3 According to paragraph 3, rain forests and savannas differ in that
A. the soils in rain forests contain fewer minerals than savanna soils do
B. savannas affect soil conditions more than rain forests do
C. unlike rain forests, savannas prefer sandy, well‐drained soils to soils that are very wet
D. unlike rain forests, savannas may develop under both very dry and very wet soil conditions
正确答案:D 解析:本段第一句就指出,rain forest 和 savannas 的土壤是相 似的,但是更极端一点。后面 就给给了 examples。最后一句 给出了两种土壤的总结“this may seem.... Either too wet or too dry for forests” 所以选 D
?Q4 The word "notably" in the passage is closest in meaning to
A. similarly
B. especially
C. usually
D. relatively
正确答案:B Notably 从 notice 发展而来, 以为显著的。因此选择 B。另 外也可通过 and 的并列格式 来推断。
Q5 According to paragraph 3, all of the following are true of savanna soils EXCEPT:
A. They have high concentrations of potassium.
B. They contain high levels of aluminum.
C. They are very acidic.
D. They contain large amounts of certain oxide minerals.
正确答案:A 这一题对应 for example 后面 的内容,A 直接和红色标注部 分矛盾,因此是要选的 except 的选项。
Paragraph 4
Waterlogged soils occur in areas that are flat or have poor drainage. These soils usually contain large amounts of clay and easily become water‐saturated. Are cannot penetrate between the soil particles, making the soil oxygen‐poor. By contrast, dry soils are sandy and porous, their coarse textures permitting water to drain rapidly. Sandy soils are prone to the leaching of nutrients and minerals and so tend to be nutritionally poor. Though, most savannas are found on sites with poor soils (because of either moisture conditions or nutrient levels of both), poor soils can and do support lush rain forest.
Q6 According to paragraph 4, which of the following is true of waterlogged soils?
A. Their upper layers are usually sandy and porous.
B. They cannot support savannas.
C. They contain little oxygen.
D. They are prone to the leaching of nutrients and minerals.
正确答案C。解析：A对应by contrast那句，sandy soil和waterlogged soil是相反的。B与原文矛盾,上段最后就说要么很干要么很湿,waterlogged就是很湿的那种。C 对应那个making the soil oxygen-poor。D 对应“Sandy soils are prone tend to be nutritionally poor. Though to .....”,而不是选项中说的 most savannas are found on sites with waterlogged soils 的特征。
Q7 The fact that "poor soils can and do support lush rain forest" suggests that:
A. poor soils alone may not be enough to explain why an area becomes a savanna
B. rain forest vegetation can significantly lower the quality of soils
C. drought stress is the single most important factor in savanna formation
D. minerals are more important than moisture for the growth of trees
正确答案 A 解析:这句话说虽然几乎全部 的 savannas 都发生在 poor soils 之上,但是 poor soils 足 以支撑茂盛的热带雨林。所以 是转折,说明 poor soils 不是 唯一决定了 savannas 的因素, 还有别的。
Paragraph 5
Most savannas probably experience mild fires frequently and major burns every two years or so. Many savanna and dry‐forest plant species are called pyrophytes, meaning they are adapted in various ways to withstand occasional burning. Frequent fire is a factor to which rain forest species seem unable to adapt, although ancient charcoal remains from Amazon forest soil dating prior to the arrival of humans suggests that moist forests also occasionally burn. Experiments suggest that if fire did not occur in savannas in the Americas, species composition would change significantly. When burning occurs, it prevents competition among plant species from progressing to the point where some species exclude others, reducing the overall diversity of the ecosystem. But in experimental areas protected from fire, a few perennial grass species eventually come to dominate, outcompeting all others. Evidence from other studies suggests that exclusion of fire results in markedly decreased plant‐species richness, often with an increase in tree density. There is generally little doubt that fire is a significant factor in maintaining savanna, certainly in most regions.
Q8 Which of the sentences below best expresses the essential information in the
?highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
A. Rain forest species seem unable to adapt to fires created by humans.
B. Ancient charcoal remains suggest that, prior to the arrival of humans, fires occurred frequently in rain forests.
C. Ancient charcoal remains in Amazon forests suggest that rain forest species adapted to the area long before the arrival of humans.
D. Rain forest species appear unable to adapt to frequent fires, but evidence from the past suggests that rain forests sometimes do burn.
正确答案:D 解析:原句主干是说 frequent fire 是造成热带雨林不能形成 的原因,即使在人类出现之前 亚马逊雨林也出现过偶尔的 燃烧。所以 D 是意思最完整 的。可根据转折关系来判断。
Q9 The word "markedly" in the passage is closest in meaning to:
A. dangerously
B. noticeably
C. rapidly
D. gradually
正确答案:B 解析:根据词根判断,原词词 根为 mark 意为标注,跟选项 中 B 的 notice 意思相近,所 以选B
Q10 Paragraph 5 supports which of the following statements regarding the importance of fires in maintaining savannas?
A. Fires prevent the growth of pyrophytes.
B. Fires eliminate some species and thus reduce the overall diversity of the ecosystem.
C. Fires that occur once every two years are unlikely to help maintain savannas.
D. Fires prevent some species from eliminating other species with which they compete.
正确答案: D
解析:对应部分从 but in experimental areas protected from fire 开始,后面的内容都 对其重要性进行了解释,如果 没有火来保持 savannas,那么 就很少有 perennial grass species 可以 outcompeting 其 他的种类,从而减少了 plant‐species 的丰富,而树的 密度则会更大。对应了 D 的 描述
Paragraph 6
On certain sites, particularly in South America, savanna formation seems related to frequent cutting and burning of moist forests for pastureland. Increase in pastureland and subsequent overgrazing have resulted in an expansion of savanna. The thin upper layer of humus (decayed organic matter) is destroyed by cutting and burning. Humus is necessary for rapid decomposition of leaves by bacteria and fungi and for recycling by surface roots. Once the humus layer disappears, nutrients cannot be recycled and leach from the soil, converting soil from fertile to infertile and making it suitable only for savanna vegetation. Forests on white, sandy soil are most susceptible to permanent alteration.
Q11 The word "subsequent" in the passage is closest in meaning to
A. expanded in area
B. harmful
C. following in time
D. repeated
正确答案: C
解析:subsequence 是后果的 意思,subsequent 就是后来, 然后的意思。因此选择 C
?Q12 According to paragraph 6, human activity affects soils in all of the following EXCEPT
A. Decomposition of leaves occurs too fast for surface roots to obtain nutrients.
B. Nutrients are not recycled.
C. Humus is destroyed.
D. Certain soils become unable to support vegetation other than savanna vegetation.
正确答案A。解析：human activity包含了cutting and burning，然后这句的后面，从increase开始就是后果，先说humus is destroyed，对应C,然后humus对于 decomposition 是非常必 要的,而 human activity destroy 了 humus,所以减慢 了 decomposition,和 A 矛盾。 后面说 nutrients cannot 被 recycled,对应了 B。converting 那一句对应了D
Evidence from other studies suggests that exclusion of fire results in markedly decreased plant‐species richness, often with an increase in tree density. There is generally little doubt that fire is a significant factor in maintaining savanna, certainly in most regions. On certain sites, particularly in South America, savanna formation seems related to frequent cutting and burning of moist forests for pastureland. Increase in pastureland and subsequent overgrazing have resulted in an expansion of savanna.
Q13 Look at the four squares【】that indicate ?where the following sentence could be added to the passage
In addition, humans have contributed to the conditions favoring the formation of savannas.
Where would the sentence best fit? Click on a square to add the sentence to the passage.
正确答案: C 解析:要插入的句子描述的是 savannas 的形成原因,并且开 头是 in addition,证明是对前 面句子的补充,前面句子说的 应该是 savannas 形成的原因 之一,对应了第二句。并且第 三空后面的句子提到了 cutting和burning,这些都是 human activity。所以选 C
Q14 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
?Several factors seem to play important roles in savanna formation.
A Savannas can form in areas with a five‐ to eight‐month wet season, but they more commonly have a longer wet season.
B Soil stress caused by drought, extreme moisture, or low nutrient levels favors the formation of savannas.
C Studies conducted in various regions indicate that an upper layer of white, sandy, soil is present in most permanent savannas.
D Drought stress affects trees and shrubs in savannas far less than it affects savanna grasses.
E Frequent fire is a major factor contributing to the formation and maintenance of savannas.
F In some areas, human cutting and burning is associated with savanna formation, and increase in pastureland has led to savanna expansion. ?
正确答案: BEF
A错误,对应原文第二段第一句，savannas有 prolong dry season。B对应原文第 二段. C 原文并没有这么说,只是说 sandy 是savannas 的一种 soil. D Savannas 本 身就树和 shrubs 就少,原文 并没有对干旱压力做出这样 的对比。E对应原文到 对第二段. F对应原文倒 数第一段。