A. they are to be back before nine in the evening B. they ought to be back before nine in the evening C. they be back before nine in the evening D. they had to be back before nine in the evening 参考答案:C 答案解析:insist表示“坚决要求”。其后的宾语从句中要用虚拟语气,其构成是should do。
第8题: [单项选择]胃穿孔的典型X线表现特征是()。 A. 胃泡扩张 B. 膈下游离气体 C. 双侧横膈抬高 D. 肠管扩张 E. 胃内有液平 参考答案:B