2017年4月20日雅思阅读预测【大范围】

　　本文2017年4月20日雅思阅读预测【大范围】，大家可以一起来了解一下，更多雅思考前预测资料及最新雅思考试资讯，欢迎关注网雅思栏目。

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　　2017年4月20日雅思阅读预测重点雅思阅读题目如下：儿童锻炼、老人智力维持、幸福心理学、决策、蚂蚁的数学、大都会电影、足部健康和垫子、幸福的科学解释、南极气候、管理学之父、霸王龙学者、声波测海洋、生物防虫法。

　　为了方便大家更好的进行雅思阅读部分的备考，本文网为大家带来了生物防虫法阅读原文及答案解析，一起来具体的了解一下吧。

　　Biological control of pests

　　The continuous and reckless use of synthetic chemicals for the control of pests which pose a threat to agricultural crops and human health is proving to be counter-productive. Apart from engendering widespread ecological disorders, pesticides have contributed to the emergence of a new breed of chemical-resistant, highly lethal superbugs.

　　According to a recent study by the Food and Agriculture Organisation (FAO), more than 300 species of agricultural pests have developed resistance to a wide range of potent chemicals. Not to be left behind are the disease-spreading pests, about 100 species of which have become immune to a variety of insecticides now in use.

　　One glaring disadvantage of pesticides’ application is that, while destroying harmful pests, they also wipe out many useful non-targeted organisms, which keep the growth of the pest population in check. This results in what agroecologists call the ‘treadmill syndrome’. Because of their tremendous breeding potential and genetic diversity, many pests are known to withstand synthetic chemicals and bear offspring with a built-in resistance to pesticides.

　　The havoc that the ‘treadmill syndrome’ can bring about is well illustrated by what happened to cotton farmers in Central America. In the early 1940s, basking in the glory of chemical-based intensive agriculture, the farmers avidly took to pesticides as a sure measure to boost crop yield. The insecticide was applied eight times a year in the mid-1940s, rising to 28 in a season in the mid-1950s, following the sudden proliferation of three new varieties of chemical-resistant pests.

　　By the mid-1960s, the situation took an alarming turn with the outbreak of four more new pests, necessitating pesticide spraying to such an extent that 50% of the financial outlay on cotton production was accounted for by pesticides. In the early 1970s, the spraying frequently reached 70 times a season as the farmers were pushed to the wall by the invasion of genetically stronger insect species.

　　Most of the pesticides in the market today remain inadequately tested for properties that cause cancer and mutations as well as for other adverse effects on health, says a study by United States environmental agencies. The United States National Resource Defense Council has found that DDT was the most popular of a long list of dangerous chemicals in use.

　　In the face of the escalating perils from indiscriminate applications of pesticides, a more effective and ecologically sound strategy of biological control, involving the selective use of natural enemies of the pest population, is fast gaining popularity — though, as yet, it is a new field with limited potential. The advantage of biological control in contrast to other methods is that it provides a relatively low-cost, perpetual control system with a minimum of detrimental side-effects. When handled by experts, bio-control is safe, non-polluting and self-dispersing.

　　The Commonwealth Institute of Biological Control (CIBC) in Bangalore, with its global network of research laboratories and field stations, is one of the most active, non-commercial research agencies engaged in pest control by setting natural predators against parasites. CIBC also serves as a clearing-house for the export and import of biological agents for pest control world-wide.

　　CIBC successfully used a seed-feeding weevil, native to Mexico, to control the obnoxious parthenium weed, known to exert devious influence on agriculture and human health in both India and Australia. Similarly the Hyderabad-based Regional Research Laboratory (RRL), supported by CIBC, is now trying out an Argentinian weevil for the eradication of water hyacinth, another dangerous weed, which has become a nuisance in many parts of the world. According to Mrs Kaiser Jamil of RRL, ‘The Argentinian weevil does not attack any other plant and a pair of adult bugs could destroy the weed in 4-5 days.’ CIBC is also perfecting the technique for breeding parasites that prey on ‘disapene scale’ insects — notorious defoliants of fruit trees in the US and India.

　　How effectively biological control can be pressed into service is proved by the following examples. In the late 1960s, when Sri Lanka’s flourishing coconut groves were plagued by leaf-mining hispides, a larval parasite imported from Singapore brought the pest under control. A natural predator indigenous to India, Neodumetia sangawani, was found useful in controlling the Rhodes grass-scale insect that was devouring forage grass in many parts of the US. By using Neochetina bruci, a beetle native to Brazil, scientists at Kerala Agricultural University freed a 12-kilometre-long canal from the clutches of the weed Salvinia molesta, popularly called ‘African Payal’ in Kerala. About 30,000 hectares of rice fields in Kerala are infested by this weed.

　　Questions 14-17

　　Choose the correct letter, A, B, C, or D.

　　Write the correct letter in boxes 14-17 on your answer sheet.

　　14 The use of pesticides has contributed to

　　A a change in the way ecologies are classified by agroecologists.

　　B an imbalance in many ecologies around the world .

　　C the prevention of ecological disasters in some parts of the the world .

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　　D an increase in the range of ecologies which can be usefully farmed.

　　15 The Food and Agriculture Organisation has counted more than 300 agricultural pests which

　　A are no longer responding to most pesticides in use.

　　B can be easily controlled through the use of pesticides.

　　C continue to spread disease in a wide range of crops.

　　D may be used as part of bio-control’s replacement of pesticides.

　　16 Cotton farmers in Central America began to use pesticides

　　A because of an intensive government advertising campaign.

　　B in response to the appearance of new varieties of pest.

　　C as a result of changes in the seasons and the climate.

　　D to ensure more cotton was harvested from each crop.

　　17 By the mid-1960s, cotton farmers in Central America found that pesticides

　　A were wiping out 50% of the pests plaguing the crops.

　　B were destroying 50% of the crop they were meant to protect.

　　C were causing a 50% increase in the number of new pests reported.

　　D were costing 50% of the total amount they spent on their crops.

　　Questions 18-21

　　Do the following statements agree with the claims of the writer in Reading Passage 2?

　　In boxes 18-21 on your answer sheet, write

　　YES if the statement agrees with the claims of the writer

　　No if the statement contradicts the claims of the writer

　　NOT GIVEN if it impossible to say what the write thinks about this

　　18 Disease-spreading pests respond more quickly to pesticides than agricultural pests do.

　　19 A number of pests are now born with an innate immunity to some pesticides.

　　20 Biological control entails using synthetic chemicals to try and change the genetic make-up of the pests’ offspring.

　　21 Bio-control is free from danger under certain circumstances.

　　Questions 22-26

　　Complete each sentence with the correct ending, A-I, below.

　　Write the correct letter, A-I, in boxes 22-26 on your answer sheet.

　　22 Disapene scale insects feed on

　　23 Neodumetia sangawani ate

　　24 Leaf-mining hispides blighted

　　25 An Argentinian weevil may be successful in wiping out

　　26 Salvinia molesta plagues

　　A forage grass.

　　B rice fields.

　　C coconut trees.

　　D fruit trees.

　　E water hyacinth.

　　F parthenium weed.

　　G Brazilian beetles.

　　H grass-scale insects.

　　I larval parasites.

　　以下是本篇阅读题目的答案解析，一起来具体的了解一下吧：

　　Question 14

　　答案: B

　　关键词: pesticides

　　定位原文: 第1段第2句“Apart from…”

　　解题思路: 题目问使用杀虫剂导致了什么。文章中说 Apart from engendering widespread ecological disorders... B 选项意思是“使得全世界许多生态系统出现不平衡”，符合文意。

　　Question 15

　　答案: A

　　关键词: Food, Agriculture Organization, more than 300

　　定位原文: 第2段第1句“According to a recent…”

　　解题思路: A 选项意思是“这些害虫已经对很多杀虫剂不再有反应了”，和文中的 resistance 对应。

　　Question 16

　　答案： D

　　关键词： cotton farmers, Central America

　　定位原文： 第4段第1、2句“The havoc that…”

　　解题思路: D 选项意思是“(棉农)为了保证更多的产量”，与原文意思相符。

　　Question 17

　　答案： D

　　关键词： mid-1960s, cotton farmers, Central America

　　定位原文： 第5段第1句“By the mid-1960s…”

　　解题思路：文章说 By the mid-1960s, the situation took an alarming turn with the outbreak of four more new pests, necessitating pesticide spraying to such an extent that 50% of the financial outlay on cotton production was accounted for by pesticides，D 选项意思是“占据了用于农业的50%的经费”，为正确答案。

　　Question 18

　　答案: NOT GIVEN

　　关键词： disease-spreading pest, agricultural pests

　　定位原文： 第2段最后1句“Not to be left behind…”

　　解题思路: 题目说传播疾病的害虫比农业害虫对杀虫剂的反应更快，但是文章中并没有对这两种害虫做比较。

　　Question 19

　　答案: YES

　　关键词： innate immunity

　　定位原文： 第2段最后1句“Not to be left behind…”

　　解题思路：题目说很多害虫天生就对杀虫剂有免疫能力，文章中说大约有100种传播疾病的害虫对各种正在使用的杀虫剂免疫，题目描述的与文章内容一致。

　　Question 20

　　答案： NO

　　关键词： biological control, synthetic chemicals, offspring

　　定位原文：第7段第1句“…a more effective and ecologically sound strategy of biological control，involving…”

　　解题思路：一种更加行之有效而健全的生态策略，即生物防虫法，就越来越受欢迎。这种策略主要是有选择性地使用害虫的天敌。通过翻译该句，考生会发现生物防虫法恰恰不涉及使用人造农药，因此题目与原文叙述相反。

　　Question 21

　　答案： YES

　　关键词： bio-control, certain circumstances

　　定位原文：第7段最后1句“When handled by…”

　　解题思路：文章说如果生态控制由专家来实施，那么它是是安全的，无污染的。题目的描述与文章一致。

　　Question 22

　　答案： D

　　关键词： disapene scale insects

　　定位原文：第9段最后1句“CIBC is also…”

　　解题思路: 破折号后面的同位语成分是对 ‘disapene scale’ insects的解释说明。defoliant指脱叶剂，考生即使不知道它的意思，也能够猜出来这种虫子危害果树。故答案为D。

　　Question 23

　　答案： H

　　关键词： Neodumetia sangawani

　　定位原文： 最后1段第3句“A natural predator…”

　　解题思路： 这道题目的解题关键是搞清楚定语从句 that was devouring forage grass 的先行词是 grass-scale insect,而不是 Neodumetia sangawani, 否则答案很容易就误选A。故答案为H。

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　　Question 24

　　答案： C

　　关键词： leaf-mining hispides

　　定位原文：最后1段第2句“...flourishing coconut groves were plagued by leaf-mining hispides...”

　　解题思路： blighted这个词很多考生不认识，不过通过上下文应该能够轻易猜出是贬义词，指的是leaf-mining hispides祸害了什么。故答案为C。

　　Question 25

　　答案: E

　　关键词: Argentinian weevil

　　定位原文: 第9段第2句“...trying out an Argentinian weevil for the eradication of water hyacinth...”

　　解题思路： wipe out的意思是“消灭”，相当于文中的 eradication, 故答案为E。

　　Question 26

　　答案： B

　　关键词： Salvinia molesta

　　定位原文： 最后1段最后两句话“By using Neochetina bruci, a beetle…”

　　解题思路：这道题目的难点在于专有名词太多，还间或有插入语或过去分词，使考生容易忽视真正的动词，比如freed和infested。代词指代成分this weed也容易被误解。如果能够将这个句子读上两遍，正确答案B也就不难找到了。

　　希望以上是网为大家整理的2017年4月20日雅思阅读预测【大范围】能够对大家备考此次雅思考试有帮助。