第18题: [单项选择]吸气性呼吸困难严重者可出现三凹征,三凹征是指() A. 胸骨上窝、锁骨上窝和肋间隙在吸气时明显下陷 B. 胸骨上窝、锁骨上窝和肋间隙在呼气时明显下陷 C. 胸骨上窝、锁骨下窝和肋间隙在吸气时明显下陷 D. 胸骨下窝、锁骨上窝和肋间隙在吸气时明显下陷 E. 胸骨上窝、锁骨下窝和肋间隙在呼气时明显下陷 参考答案:A
第33题: [单项选择]I could find my umbrella nowhere. I ______ it in the taxi. A. should leave B. must have left C. could leave D. should have left 参考答案:B 答案解析:mush have done表示推测,对过去的行为进行猜测。should have done指本该做而没做某事。