The river is rising.It last night.
问题描述：
The river is rising.It last night.
A.must be raining B.must rain C.mighthave rained D.must have rained
答
D.must have rained
对过去的事情作以肯定推测,用must(may)+ have + 过去分词那为什么不选C从语境看“河水正在上涨“，可见，这个推测是极为肯定的，即”昨晚一定（而不是“可能”）下过雨“