Tom, we wouldn’t have been late for the last bus.
A. If we didn’t wait for
B. If we haven’t waited for
C. we hadn’t waited for
D. Had we not waited for
网友回答
A. If we didn’t wait for
B. If we haven’t waited for
C. we hadn’t waited for
(答案→)D. Had we not waited for
解析：考查虚拟语气及倒装。此题是与过去事实相反的虚拟语气，If 条件句中的If 省略，助动词had要前提，句意：如果我们不等汤姆，最后一辆公交车我们就不会迟到。所以选D。