Question

—How was the professor's lecture?
—Impressive. Thank you so much for giving me a lift during the rush hours. If not, I ________ the lecture today.

A．couldn't attend	B．might not have attended
C．mustn't have attended	D．can't have attended

Answer 1

B

考察情态动词的虚拟语气。根据句意可知，该句是对过去的虚拟，故排除A。句意为如果不是你给的便车，我可能就无法参加今天的讲座了。
C意为禁止参加 D意为不可能参加。