The police still haven't found the lost child, but they're doing all they _______.
问题描述:
The police still haven't found the lost child, but they're doing all they _______.
can/may/must/may答案是can.
请问为什么不选should?
答
all they can是说他们所能做的全部
should是应该的意思 all they should 是他们应该做的
结合语意 这里要表达的应该是警察仍然没有找到这个丢失的孩子,但是他们已经做了他们可以做的全部,而不是他们应该做的全部.