Research findings show we spend about two hours dreaming every night, no matter what we ____ have done during the day
A.shouldB.wouldC.mayD.must在线课程C
考查情态动词。句意“研究结果显示，我们每晚要花两个小时的时间做梦，无论白天做了什么事情。”should have done“本应该做某事”；would have done用于对过去事实的虚拟；may have done“可能已经做了某事”；must have done“一定已经做了某事”。这里表示“可能”。故选C。