奇怪现象:Such burrowing discourages barnacles from clinging to their shells即一般juvenile horseshoe crabs 会附着 barnacles 。但是, juvenile horseshoe crabs are found not to have significant barnacle populations, even though they seldom burrow(这排除BURROW使它们没有附着barnacle的原因)。所以你要找另外原因解释 found not to have significant barnacle 。E的意思为 juvenile horseshoe crabs ( Until they are fully grown指在他们长大前)一年有几次脱旧壳,长新壳。所以上面的barnacle都给脱掉了,当然没发现 barnacle 。
做模考的时候急急忙忙随便猜了一个,当然猜错啦。回头总结的时候,我是这么想的,b那个东西文中说得很清楚是clinging to their shells,问题要解释的对象是b这个东西在蟹身上的多少,那么基本上答案应该在蟹壳上做文章,这样锁定A和E,A纯属废话,没给出实质性原因,再看E,解释得通,果然是答案。这样,如果把“蟹壳”作为切入点,比较容易找到答案。