―Theaccidentmightnothavehappened,hadwebeenmorecareful....

问题详情：

 ―The accident might not have happened, had we been more careful.     

 ―But we ______.

        A. weren’t                  B. didn’t                       C. hadn’t                      D. don’t

【回答】

A

知识点：虚拟语气与情态动词

题型：选择题