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标题: PREP 07 CR 第五题老虎鲨 [打印本页]

作者: 84387889 时间: 2012-5-15 16:26
标题: PREP 07 CR 第五题老虎鲨

5.(24371-!-item-!-188;#058&000859)

Tiger sharks are common in the waters surrounding Tenare Island

.Usually tiger sharks feed on smaller sharks, but sometimes they have attacked tourists swimming and surfing at Tenare's beaches.This has hurt Tenare's tourism industry, which is second only to its fishing industry in annual revenues.In order to help the economy, therefore, the mayor of the island has proposed an ongoing program to kill any tiger sharks within a mile of the beaches.

Which of the following, if true, most strongly calls into question the likelihood that implementation of the mayor's proposal will have the desired consequence?

(A) Even if not all the tiger sharks that come close to the beaches are killed, the existence of the program would reassure tourists.

(B) Business owners who depend on tourism are willing to pay most of the cost of implementing the program.

for its beaches, even though the island features a number of other tourist attractions.

(D) The small sharks on which tiger sharks prey feed on fish that are commercially important to the island's fisheries.

(E) Not all tourists who come to Tenare Island

enjoy swimming or surfing.

答案是D，但是想不通：为啥“虎鲨吃掉小鲨鱼，小鲨鱼吃鱼，这些鱼也是经济基础，如果没有了虎鲨也就没有了鱼”会影响经济，如果没有虎鲨吃掉小鲨鱼，小鲨鱼吃鱼，那不是最后的小小鱼就会越来越多，而经济会越来越好吗？还是因为食物链的问题？如果是食物链也应该是反作用才有用呀？？？哪位好心人帮个忙吧！！！

作者: DUKB24 时间: 2012-5-15 22:09
虎鲨少了，（虎鲨是小鲨鱼的天敌）小鲨鱼自然就多了，小鲨鱼跑去吃鱼（小鲨鱼是鱼的天敌），鱼少了（但是鱼对地区的经济很重要）就削弱了..LZ是不是哪里理解错了

作者: 84387889 时间: 2012-5-16 15:09

虎鲨少了，（虎鲨是小鲨鱼的天敌）小鲨鱼自然就多了，小鲨鱼跑去吃鱼（小鲨鱼是鱼的天敌），鱼少了（但是鱼对地区的经济很重要）就削弱了..LZ是不是哪里理解错了

-- by 会员 DUKB24 (2012/5/15 22:09:56)

啊！！！！谢谢！现在我理解了！万分感谢！

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