◎ 题干
— Where is Bob? I cannot find him anywhere.
— He ________ have been off long. I heard him make a call just now.
 [     ]
A. shouldn't  
B. can't
C. mustn't  
D. needn't
◎ 答案
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“— Where is Bob? I cannot find him anywhere.— He ________ have been off long. I heard him make a call just now.[ ] A. shouldn'tB. can'tC. mustn'tD. nee…”主要考查了你对  【情态动词】  等知识点的理解和应用能力。关于这些知识点的“档案”,你可以点击相应的链接进行查看和学习。