59. In order to withstand tidal currents, juvenile horseshoe crabs frequently burrow in the sand. Such burrowing discourages barnacles from clinging to their shells. When fully grown, however, the crabs can readily withstand tidal currents without burrowing, and thus they acquire substantial populations of barnacles. Surprisingly, in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have signifi cant barnacle populations, even though they seldom burrow.
Which of the following, if true, most helps to explain the surprising fi nding?
Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.
(B) Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.
(C) The strength of the tidal currents in a given location varies widely over the course of a day.
(D) A very large barnacle population can signifi cantly decrease the ability of a horseshoe crab tofi nd food.
(E) Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.
题目里面要求解释the surprising finding，即文章中的"surprisingly, in areas where
tidal currents are very weak, juvenile horseshoe crabs are found not to have
significant barnacle populations, even though they seldom burrow."说来说去，它问你
的地方和成熟螃蟹是没有关系的。文章里面也说了，"when fully grown, however, the crabs
can readily withstand tidal currents without burrowing, and thus they acquire
substantial populations of barnacles."成熟螃蟹上barnacles本来就很多，不需要你说明不
多。作者: xiaoaojiang 时间: 2010-8-21 19:38
这道题我也想问，为什么A不对呢？？作者: EGHJUYMN 时间: 2010-8-22 07:29
假设A成立，海浪不把crabs身上的barnacles冲走。那么在没有海浪或者海浪很弱的时候，crabs身上不应该满身都是barnacles吗？跟文章里面讲的"in areas where tidal currents are very weak, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow"矛盾了吧。
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