再来一题：希望新东方给的答案是错的

The chanterelle, a type of wild mushroom, grows beneath host trees such as the Douglas fir, which provide it with necessary sugars. The underguound filaments of chanterelles, which extract the sugars,in turn provide nutrients and water for their hosts. Because of this mutually beneficial relationship, harvesting the chanterelles growing beneath a Douglas fir seriously endangers the tree.

which of the following, if true, casts the most doubt on the conclusion drawn above?

a. the number of wild mushrooms harvested has increased in recent years.

b.Chanterelles grow not only beneath Douglas firs but also beneath other host trees.

c.many types of wild mushrooms are found only in forests and cannot easily be grown elsewhere.

d.the harvesting of wild mushrooms stimulates future growth of those mushrooms

e.young douglas fir seedlings die without the nutrients and water provided by chanterelle filaments.

"correct" answer

结论说种chanterelles会危害douglas fir.

E choice说没有chanterelle, douglas fir 就会死，不就是说chanterelles不会危害douglas fir 吗，这不就削弱结论了吗？

D 跟原文结论根本无关啊

汗!!原文说harvesting chanterelles会危害douglas fir

你刚好反了

原文主体说chanterelle和douglas fir 互惠互利，怎么结论却得出种前者会危害后者呢？

The chanterelle, a type of wild mushroom, grows beneath host trees such as the Douglas fir, which provide it with necessary sugars. The underguound filaments of chanterelles, which extract the sugars,in turn provide nutrients and water for their hosts. Because of this mutually beneficial relationship, harvesting the chanterelles growing beneath a Douglas fir seriously endangers the tree.

你再仔細讀一遍，原文說該mushroom提供養份跟水給fir，所以推論說若去把該mushroom收割下來(harvest)，那該mushroom減少了，必定會危害到fir的生存。題目問如何削弱結論，D選項說收割了mushroom會刺激mushroom的增長，反而對fir有利，為有因無果的削弱(A-收割→NB-fir增長)，故D沒錯

E選項以收割確實有害於fir的樹苗證實該結論，為加強選項