◎ 题干
--- Listen! David is talking happily with his mother in the next room.
 --- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.
A.shouldB.mustC.can’tD.mustn’t
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◎ 解析
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◎ 知识点
    根据n多题专家分析,试题“--- Listen! David is talking happily with his mother in the next room.--- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.A.shouldB.m…”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。