Question

—Look, John’s fallen asleep.

— Oh, he _______ too late last night.

A. might sit up     B. should have sat up      C. could sit up           D. must have sat up

Answer 1

D

解析:

从by now看应该是完成时态，排除B、C，从It usually takes four days看，应是ought to“应该”，选D。