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2018年4月15日托福千赢国际手机版下载写作千赢国际娱乐老虎机回忆

中华千赢国际手机版下载网   2018-04-16   【

2018年4月15日托福千赢国际手机版下载写作千赢国际娱乐老虎机回忆

  综合

  总论点:Red palm weevil is a kind of pest which feeds on the leaves and trunks of palm. It originates in tropical forest of Asia,and spread all over the world. So experts are studying how to control the spread of weevils.

  阅读观点:There are three possible ways.

  1、cut down the infested trees

  Once the palm trees are infested, they will show symptoms like yellow leaves and holes on the trunks. If the infested trees are cut down as soon as possible, then the weevils can be prevented from spreading.

  2、Use pheromone mixture to trap pest

  Weevils will be attracted by the pheromone mixture and be caught in the traps. Then they will be killed by the toxic substance put in the trap.

  3、use pesticides

  weevils can be killed through spraying the pesticides on trunks and the soil.

  听力观点:Controlling the spread of weevils is still a challenging task, and all the solutions have weakness.

  1、Firstly, the symptoms of infestation is hard to monitor in the initial period of time. When the palm tree shows symptom like yellow leaves, actually it has been infested for almost one month, and weevils have had enough time to reproduce. So it is useless to destroy the infested trees because the weevils have already moved on to infest other trees.

  2、The poisonous chemicals in traps could not stay active for a long time. To make the traps work, people should replenish the traps each week. If the traps are not replaced regularly, the weevils would not be killed and so they will spread in the surrounding area.

  3、There are hundreds of weevils living deep inside the trees. Even though pesticides are applied thoroughly to reach the deep inside trees, some weevils would survive . And any surviving female can lay more than 200 eggs at a time. As a result, they can produce enough offspring to keep doing serious damage to many trees.

  独立

  Do you agree or disagree with the following statement?

  Playing sports can teach people lessons about the life.

  Use specific reasons and examples to support your answer.

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