I did not hear the phone,I___asleep.A.must be B.must have been C._英语解答

I did not hear the phone,I___asleep.A.must be B.must have been C.should be D.should have been

人气：203 ℃　时间：2019-11-10 16:10:11

解答

选B
must have been 是对过去的猜测,我没听见电话响,我一定是睡着了.那A不行吗？A表示对现在的推测，而前一句用的是过去式。