but he has to 【】 his homework first A.do B.does C.doing D,is doing

问题描述:

but he has to 【】 his homework first A.do B.does C.doing D,is doing

A 。have to do sth,不得不做某事。固定结构!

have to do sth里的do要用动词原形,所以选择A

A has to do sh不得不做某事,是have to do sth 的第三人称单数形式