Question

【题目】It is cold in the room. They ______ have turned off the heating.
A.must
B.ought to
C.should
D.could

Answer 1

【答案】A
【解析】句意：房间很冷，他们一定关了暖气。must have+过去分词，过去一定做过某事；ought to have +过去分词=should have+过去分词，表示过去“本来应该做的事情没有做。”could have+过去分词表示过去本来能够做的事情没有做。根据句意可知选A。