19.I didn't hear the phone .I ______asleep .19.I didn't hear the phone .I ______asleep .A.must be B.must have been C.should be D.should have been 选B为什么为什么不选A

问题描述:

19.I didn't hear the phone .I ______asleep .
19.I didn't hear the phone .I ______asleep .
A.must be
B.must have been
C.should be
D.should have been
选B为什么
为什么不选A