定于从句练习The doctor did all_to save de wounded boy.A.what he could B_英语解答

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?

人气：277 ℃　时间：2020-05-26 00:32:28

解答

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 ...