Question

【題目】—It's already twelve o'clock, and he ____________ have been here half an hour ago.
—Maybe his flight was behind time.
A.must
B.ought to
C.may
D.can

Answer 1

【答案】B
【解析】句意：——現在已經12點了。他半個小時之前就應該到這兒了。——也許他的飛機晚點了。根據對話內容，尤其是＂Maybe his flight was behind time.＂可知，用ought to/should have done sth結構表示＂過去本應該做某事而實際上沒有做＂。故選B。