题目内容：

If he _____to the teacher carefully,he______ the answer to the question now.
A.had listened,would have known
B.listened,would know
C.listened,would have known
D.had listened,would know

优质解答

D.had listened,would know
如果他认真的听老师讲了,他现在就应该知道答案了.
前半句,与过去相反,用过完; 后面与现在相反,用过去式 或过去将来.

追问：

是和虚拟语气有关吗？ 谢谢

追答：

嗯,看我的翻译,就知道,是虚拟语气了.