◎ 题干
Look! The light in the room is still on. Mr. Liu          at work.
[     ]
A. must
B. can't be
C. must be
D. have to be
◎ 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“Look! The light in the room is still on. Mr. Liuat work.[ ]A. mustB. can't beC. must beD. have to be…”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。