If he ___ to the teacher attentively, he ___ the answer to the problem now.
A. had listened, would have known B. listened, would know
C. listened, would have known D. had listened, would know
If he ___ to the teacher attentively, he ___ the answer to the problem now.
A. had listened, would have known B. listened, would know
C. listened, would have known D. had listened, would know