Q33:

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 significant barnacle populations, even though they seldom burrow.

Which of the following, if true, most helps to explain the surprising finding?

1. Tidal currents do not themselves dislodge barnacles from the shells of horseshoe crabs.

2. Barnacles most readily attach themselves to horseshoe crabs in areas where tidal currents are weakest.

3. The strength of the tidal currents in a given location varies widely over the course of a day.

4. A very large barnacle population can significantly decrease the ability of a horseshoe crab to find food.

5. Until they are fully grown, horseshoe crabs shed their shells and grow new ones several times a year.

   Answer: E

不理解，请NN指点

A说Tidal currents不防碍barnacles贴在螃蟹的壳上，那么应该更可能在螃蟹壳

上发现大量barnacles。
B与事实相反
C中潮汐力量的变化与需要解释的现象无关
D中说大量的barnacles让螃蟹找食物的能力下降，无关
E说成年螃蟹一年中没事老换新壳，旧壳上的barnacles自然就随着脱落了。没有

barnacles的堆积，数量就不会很多～
大概是这样吧

E说成年之前螃蟹一年中老换新壳，旧壳上的barnacles自然就随着脱落了。So no matter where they are, they are not going to have significant barnacle populations.

Does that make sense?

这个题是这样：

潮汐的出现呢，使得年轻的蟹老是要挖洞来保持自己在潮汐里能站稳，这样的挖洞的动作呢，使得barnacles 这个破东西不和它的壳粘连，意思是barnacles 这个东西年轻的蟹的壳上数量很少。

当成年后呢，蟹就不用挖洞了，barnacles 这种东西就越来越多的集中在壳上了。

逻辑：潮汐多－－－挖洞－－－barnacles 在壳上不粘连。不挖洞－－－barnacles 这种东西就在壳上狂长。

但是呢，发现了一个现象：潮汐少－－－不挖洞－－－barnacles 在壳上还是少。照道理不挖洞－－barnacles 应该多。

选一个能解释的选项：E说年轻的蟹一直换壳，旧的壳上的barnacles 随换壳脱去了，所以年轻蟹－－－不挖洞－－barnacles 还是少。

希望我说明白了

谢谢!明白了

考点也太绕弯了,"所以年轻蟹－－－不挖洞－－barnacles 还是少",要进行多次推理

.

ETS他们也不想想,非洲兄弟考生根本就没见过海,更没见过螃蟹,他们出这样的题却声

明不考任何专业知识和背景知识.而事实上确是对美国考生最有利(美国两边都是海岸

线),这就是歧视,不管是有意还是无意的. 建议非洲兄弟保留诉之于法律的权利