定于从句练习The doctor did all_to save de wounded boy.A.what he could B.he could C.everything which he could D.for which he could 为啥选B?先行词all 在从句中做什么成分呢?为什么不是填he could do?
问题描述：
定于从句练习
The doctor did all_to save de wounded boy.
A.what he could B.he could C.everything which he could D.for which he could
为啥选B?先行词all 在从句中做什么成分呢?为什么不是填he could do?
答
all在这里作宾语。这里could后面需要跟一个不定式来做补充，而绝不能跟动词。至于A中的what，我想你应该明白，这里定语从句的引导词是省略的，其他的就更离谱了。
答
选项里面没有he could do.
有的话也是可以的。
答
先行词在从句中是不做成分的,完整的从句是：the doctor did all that he could did to save the wounded boy.但是主语 the doctor 后面已经有一个did了,所以从句中的did被省略了,所以此处 he could 和 he could do ...