第4题: [单项选择]梗阻性化脓性胆管炎最常见的梗阻原因是( ) A. 肝脓肿胆道出血阻塞胆管 B. 急性胆囊炎胆囊肿大压迫胆总管 C. 胆管狭窄 D. 胆管结石 E. 胆管肿瘤 参考答案:D
第5题: [单项选择]Tom ______ the meeting last night, but he didn't as he suddenly fell ill. A. had attended B. should have attended C. could have attended D. must have attended 参考答案:B 答案解析:[分析] 在谈到那些本该发生而没有发生的事时, should或ought to应与不定式的完成式形式连用。例如:The plant is dead. Maybe I should have given