If the salinity of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation —— conversion of liquid water to water vapor. In this manner, the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff.
Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.
A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water.
In the Weddell Sea, off Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.
4l. What does the passage mainly discuss?
(A) The elements of salt
(B) The bodies of water of the world
(C) The many forms of ocean life
(D) The salinity of ocean water
42. The word "this" in line 5 refers to
(A) ocean
(B) evaporation
(C) salinity
(D) crystals
43. According to the passage, the ocean generally has more salt in
(A) coastal areas
(B) tropical areas
(C) rainy areas
(D) turbulent areas
44. All of the following are processes that decrease salinity EXCEPT
(A) evaporation
(B) precipitation
(C) runoff
(D) melting
45. Which of the following statements about the salinity of a body water can best be
inferred from the passage?
(A) The temperature of the water is the most important factor.
(B) The speed with which water moves is directly related to the amount of salt.
(C) Ocean salinity has little effect on sea life.
(D) Various factors combine to cause variations in the salt content of water.
46. The word "altered" in line 16 is closest in meaning to
(A) determined
(B) changed
(C) accumulated
(D) needed
47. The world "it" in line 18 refers to
(A) sea ice
(B) salinity
(C) seawater
(D) manner
48. Why does the author mention the Weddell Sea?
(A) To show that this body of water has salinity variations
(B) To compare Antarctic waters with Arctic waters
(C) To give an example of increased salinity due to freezing
(D) To point out the location of deep waters
49. Which of the following is NOT a result of the formation of ocean ice?
(A) The salt remains in the water.
(B) The surrounding water sinks.
(C) Water salinity decreases.
(D) The water becomes denser.
50. What can be inferred about the water near the bottom of oceans?
(A) It is relatively warm.
(B) Its salinity is relatively high.
(C) It does not move.
(D) It evaporates quickly.#p#副标题#e#
托福阅读模拟试题:冰川国家公园
Glacier National park in Montana shares boundaries with Canada, an American Indian reservation, and a national forest. Along the North Fork of the Flathead River, the park also borders about 17,000 acres of private lands that are currently used for ranching, timber, and agriculture. This land is an important part of the habitat and migratory routes for several endangered species that frequent the park. These private lands are essentially the only ones available for development in the region.
With encouragement from the park, local landowners initiated a land-use planning effort to guide the future of the North Fork. The park is a partner in an interlocal agreement that calls for resource-managing agencies to work together and with the more than 400 private owners in the area. A draft plan has been prepared, with the objective of maintaining traditional economic uses but limiting new development that would damage park resources. Voluntary action by landowners, in cooperation with the park and the county, is helping to restrict small-lot subdivisions, maintain wildlife corridors, and minimize any harmful impact on the environment.
The willingness of local landowners to participate in this protection effort may have been stimulated by concerns that Congress would impose a legislative solution.
Nevertheless, many local residents want to retain the existing character of the area.
Meetings between park officials and landowners have led to a dramatically improved understanding of all concerns.
31. The passage mainly discusses
(A) the endangered species in Glacier National Park
(B) the protection of lands surrounding Glacier National Park
(C) conservation laws imposed by the state of Montana
(D) conservation laws imposed by Congress
32. Why are the private lands surrounding Glacier National Park so important?
(A) They function as a hunting preserve.
(B) They are restricted to government use.
(C) They are heavily populated.
(D) They contain natural habitats of threatened species.
33. The word "ones" in line 6 refers to
(A) private lands
(B) endangered species
(C) migratory routes
(D) ranching, timber, agriculture
34. The word "initiated" in line 7 is closest in meaning to
(A) started
(B) requested
(C) purchased
(D) considered
35. The relationship between park officials and neighboring landowners may best be
described as
(A) indifferent
(B) intimate
(C) cooperative
(D) disappointing
36. It can be inferred from the passage that a major interest of the officials of Glacier
National Park is to
(A) limit land development around the park
(B) establish a new Park in Montana
(C) influence national legislation
(D) settle border disputes with Canada
37. In lines 15-16, the author implies that landowners might be responding to environmental
concerns for which of the following reasons?
(A) They wish to stimulate economic growth.
(B) They wish to improve their public image.
(C) They have a tradition of cooperating with the government.
(D) They fear federal legislation.
38. The word "stimulated" in line 16 is closest in meaning to
(A) motivated
(B) anticipated
(C) substituted
(D) undermined
39. The word "retain" in line 17 is closest in meaning to
(A) preserve
(B) possess
(C) enjoy
(D) improve
40. Where in the passage does the author mention the purpose of the plan developed
by local landowners and park officials?
(A) Lines 1-2
(B) Lines 4-6
(C) Lines 10-14
(D) Lines 15-17#p#副标题#e#
托福阅读模拟试题:统计学
There were two widely divergent influences on the early development of statistical methods. Statistics had a mother who was dedicated to keeping orderly records of governmental units (state and statistics come from the same Latin root, status) and a gentlemanly gambling father who relied on mathematics to increase his skill at playing the odds in games of chance. The influence of the mother on the offspring, statistics, is represented by counting, measuring, describing, tabulating, ordering. and the taking of censuses —— all of which led to modern descriptive statistics. From the influence of the father came modern inferential statistics, which is based squarely on theories of probability.
Descriptive statistics involves tabulating, depicting, and describing collections of data. These data may be quantitative, such as measures of height, intelligence, or grade level - variables that are characterized by an underlying continuum - orthe data may represent qualitative variables, such as sex, college major, or personality type. Large masses of data must generally undergo a process of summarization or reduction before they are comprehensible. Descriptive statistics is a tool for describing or summarizing or reducing to comprehensible form the properties of an otherwise unwieldy mass or data. Inferential statistics is a formalized body of methods for solving another class of problems that present great difficulties for the unaided human mind. This general class of problems characteristically involves attempts to make predictions using a sample of observations. For example, a school superintendent wishes to determine the proportion of children in a large school system who come to school without breakfast, have been vaccinated for flu, or whatever. Having a little knowledge of statistics, the superintendent would know that it is unnecessary and inefficient to question each child; the proportion for the entire district could be estimated fairly accurately from a sample of as few as l00 children. Thus, the purpose of inferential statistics is to predict or estimate characteristics of a population from a knowledge of the characteristics of only a sample of the population.
21. With what is the passage mainly concerned ?
(A) The drawbacks of descriptive and inferential statistics
(B) Applications of inferential statistics
(C) The development and use of statistics
(D) How to use descriptive statistics
22. The word "divergent" in line 1 is closest in meaning to
(A) different
(B) distributed
(C) recorded
(D) prominent
23. According to the first paragraph, counting and census-taking arc associated with
(A) inferential statistics
(B) descriptive statistics
(C) unknown variables
(D) qualitative changes
24. Why does the author mention the "mother" and "father" in the first paragraph?
(A) To point out that parents can teach their children statistics
(B) To introduce inferential statistic
(C) To explain that there are different kinds of variables
(D) To present the background of statistics in a humorous and understandable way
25. The word "squarely" in line 8 could best be replaced by
(A) solidly
(B) geometrically
(C) rectangularly
(D) haphazrardly
26. Which of the following is NOT given an example of a qualitative variable?
(A) Gender
(B) Height
(C) College major
(D) Type of personality
27. The word "they" in line 13 refers to
(A) variables
(B) masses
(C) descriptive statistics
(D) properties
28. Which of the following statements about descriptive statistics is best supported by the
passage?
(A) It reduces large amounts of data to a more comprehensible form.
(B) It is based on probability.
(C) It can be used by people with little knowledge of mathematics.
(D) It measures only qualitative differences.
29. The word "unwieldy" in line 15 is closest in meaning to
(A) unmanageable
(B) unpredictable
(C) understandable
(D) unreliable
30. According to the passage, what is the purpose of examining a sample of a population?
(A) To compare different groups
(B) To predict characteristics of the entire population
(C) To detect differences not observable in the whole population
(D) To compile more accurate data#p#副标题#e#
托福阅读模拟试题:生态系统的长期稳定
11.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incurred choices change the meaning in important ways or leave out essential information.
○Ecologists now think that the stability of an environment is a result of diversity rather than patchiness.
○Patchy environments that vary from place to place do not often have high species diversity.
○Uniform environments cannot be climax communities because they do not support as many types of organisms as patchy environments.
○A patchy environment is thought to increase stability because it is able to support a wide variety of organisms.
12.The word “adjacent” in the passage is closest in meaning to
○Foreign
○Stable
○Fluid
○Neighboring
Paragraph 6: Ecologists are especially interested to know what factors contribute to the resilience of communities because climax communities all over the world are being severely damaged or destroyed by human activities. The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans. We need to know what aspects of a community are most important to the community’s resistance to destruction, as well as its recovery.
13.Look at the four squares [ ] that indicate where the following sentence could be added to the passage.
In fact, damage to the environment by humans is often much more severe than damage by natural events and processes.
Where would the sentence best fit? Click on a square to add the sentence to the passage.
14.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.
The process of succession and the stability of a climax community can change over time.
Answer choices
○The changes that occur in an ecosystem from the pioneer to the climax community can be seen in one human generation.
○A high degree of species diversity does not always result in a stable ecosystem.
○The level of resilience in a plant community contributes to its long-term stability.
○Ecologists agree that climax communities are the most stable types of ecosystems.
○Disagreements over the meaning of the term “stability” make it difficult to identify the most stable ecosystems.
○The resilience of climax communities makes them resistant to destruction caused by humans.