题目内容
—I saw your mother in the library just now.
—It ______ be her. She went to Beijing yesterday.
A. can't B. mustn't
C. needn't D. must
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题目内容
—I saw your mother in the library just now.
—It ______ be her. She went to Beijing yesterday.
A. can't B. mustn't
C. needn't D. must