请教SC一提

qianjeanne

    

这道题GWD的答案选A,我觉得A中each of which后面应该用单数才对。请教大牛讲解

    

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.