E 为什么不对呢？

When an active tooth in the shark’s jaws is lost or worn down, many spare teeth lie in seemingly limitless reserve, each of which are ready to slide into the appropriate position.

1. When an active tooth in the shark’s jaws is lost or worn down, many spare teeth lie in seemingly limitless reserve, each of which are ready to slide into the appropriate position.
2. Whenever an active tooth is lost or worn down, many spare teeth lie in seemingly limitless reserve in the shark’s jaws, which are each ready to slide into the appropriate position.
3. Many spare teeth lie in seemingly limitless reserve in the shark’s jaws, each one of which are ready to slide into the appropriate position when an active tooth is lost or worn down.
4. The many spare teeth lying in seemingly limitless reserve in the shark’s jaws, each one of which is ready to slide into the appropriate position whenever an active tooth is lost or worn down.
5. In the shark’s jaws, many spare teeth lie in seemingly limitless reserve, each one ready to slide into the appropriate position whenever an active tooth is lost or worn down.

答案是A

I don't know where you got this problem from, but to me, A should be the correct answer.

What is your question, by the way?

"E" seems a better choice to me. In "A", the "are" in "each of which are" seems wrong, it should be "is" instead.

Fusiyu, may I ask where did you get this SC question from? Thanks!

...each of which are...

这个which 指代的是什么？ 在each后面怎么用are 呢？

to me, E is best.

说是天山GWD31的那套。第2个test, 第34题。搜了半天，没找到讨论。 这个set, 还有几个答案给的相当的不靠谱。我都提上来了，欢迎讨论。

E should be the right answer. each one ready 的用法应该和现在(过去)分词做形容词时修饰句子的主语一样,和reserve放在一起不会指代不清.