问题补充：
The ground is all wet. It last night.
A. can’t have rained
B. may have rained
C. can have rained
D. must have rained
答案：
A. can’t have rained
B. may have rained
C. can have rained
(答案→)D. must have rained
解析：考查情态动词表推测。时间是last night，所以要用情态动词加完成时态表对过去事实的推测。can’t have rained表不可能下雨，和前一句矛盾，排除A；may have rained可能下雨了，把握性不大，和前一句不符，排除B；can不能用于肯定句表推测，排除C；所以选D，must have rained肯定下雨了，把握性很大，符合句意。
