Certainly no creature in the sea is odder than the common sea cucumber(海参). All living creatures, especially human beings, have

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问题 Certainly no creature in the sea is odder than the common sea cucumber(海参). All living creatures, especially human beings, have their peculiarities, but everything about the little sea cucumber seems unusual. What else can be said about an odd animal that, among other eccentricities,  eats mud, feeds almost continuously day and night but can live without eating for long periods, and can be poisonous hut is considered supremely edible by gourmets(美食家) ?
   For some fifty million years, despite all its eccentricities, the sea cucumber has subsisted on its diet of mud. It is adaptable enough to live attached to rocks by its tube feet, under rocks in shallow water, or on the surface of mud fiats. Common in cool water on both Atlantic and Pacific shores, it has the ability to suck up .mud or sand and digest whatever nutrients are present.
   Sea cucumbers come in a variety of colors, ranging from black to reddish-brown to sandcolor and nearly white. One form even had vivid purple tentacles. Usually the creatures are cucumbers-shaped——hence their name——and because they are typically rock inhabitants, this shape, combined with flexibility, enables them to squeeze into narrow cracks where they are safe from predators and ocean currents.
   Although they have voracious appetites, eating day and night, sea cucumbers have the capacity to become inactive and live at a low metabolic rate feeding sparingly or not at all for long periods, so that the marine organisms that provide their food have a chance to multiply. If it were not for this faculty, they would devour all the food available in a short time and would probably starve themselves out’ of existence.
   But the most spectacular thing about the sea cucumber is the way it defends itself. Its major enemies are fish and crabs, when attacked, it squirts all its internal organs into the water. It also casts off attached structures such as tentacles. The sea cucumber will eviscerate排除内脏) and regenerate itself if it is attacked or even touched; it will do the same if the surrounding water temperature is too high or if the water becomes too polluted.

选项 A、the reason for the sea cucumber’s name
B、ways to identify the sea cucumber
C、places where the sea cucumber can be found
D、the peculiarities that make the sea cucumber unusual

答案D

解析 本文的主题句是第一段第一句:毫无疑问,没有哪一种海洋动物能比常见的海参更为奇特的了。文章的其余部分均是围绕这句话而展开的,说明海参的种种奇特之处。
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