If there is a strike of bus drivers, they ________ walk to school tomorrow．

If there is a strike of bus drivers, they ________ walk to school tomorrow．

A.may have to

B.must have to

C.may have

D.must have

答案及解析： A

解析：

have to意为“不得不”。可以用在may之后，但是不能用在must之后。