Question

【题目】He seldom stays up late at night, ______ necessary, to keep himself full of energy the next day.

A. if B. unless C. until D. while

Answer 1

【答案】B

【解析】句意：除非必要，否则他很少熬夜，以便第二天保持充沛的精力。考查连词辨析题。if如果，表条件；B. unless除非，表条件；C. until直到……才，表时间；D. while当……的时候，表时间。本句表条件，根据句意语境，可知if不合句意，故选B。