Question

【题目】I didn't hear the phone. I ______ asleep.
A.must be
B.must have been
C.should be
D.should have been

Answer 1

【答案】B
【解析】句意：我没听到电话，我一定睡着了。must be一定，对现在情况的肯定猜测；must have been一定，对过去情况的肯定猜测；should be（按常理）应该；should have been本应该做的事而没有作。句中didn't是过去式，根据句意可知选B。