答案：D

题目分析：考查推测，would have done意思“对过去为发生事情的推测”，句子意思“我可能一会将要来，但是我不知道他们一直等我”，所以选D

点评：推测是个难点。would have done意思“对过去为发生事情的推测”；must have done表示一定做过什么；may have done表示可能做过什么。句子I didn’t know that they were waiting for me．是个宾语从句，引导词that可以省去。