Question

一I still cannot figure out why he missed his flight．
一He       an accident on the way to the airport．

1. A.
   could have had
2. B.
   should have had
3. C.
   would haye had
4. D.
   must have had

Answer 1

A
考查情态动词和虚拟语气。“我仍然不理解他是怎么错过航班的。”“他可能在去机场的路上遇到事故了。”could have done表示不太肯定的推测，“可能已经做了某事”；should have done“本应该做某事”；D“一定已经做了某事”。根据答语可知，表示的是不太肯定的推测。故选A。