Look at the boy standing under the tree.Is it Neil?

问题描述:

Look at the boy standing under the tree.Is it Neil?
Yes,it _____ be him.
A.must B.can't C.may D.mustn't
请说明原因,

选A.回答问题的说的是yes,表示答案是肯定的.B是那不可能是他,与yes矛盾.may表示可能,没有must肯定意味强.通常回答不可能不用mustn't,用can't