说明
must 作“必须”解, mustn't 作“不允许”解时的附加疑问句
核心问题
We must help the old woman, ____ we?
A. mustn't B. must C. needn't D. need
我选了 C, 因为 must 的否定形式是 needn't。
词典解答
选 C 当然是正确的,但是选 A 也是正确的。因为当 must 作“必须”解时,也可以用 mustn't 构成附加疑问句:
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They must clean the floor, mustn't/needn't they? 他们必须擦地板,是不是?
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We must stay home, mustn't we? 我们必须留在家里,是不是?
当 mustn't 作“不允许”解时,则可以用 must 或 may 构成附加疑问句:
We mustn't be late, must/may we? 我们不许迟到,是不是?
练习题
请做下面的英语试题：
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You mustn't tell it to your mother, ____? A. must you B. do you C. need you D. will you
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The students must hand in their term papers in a week, ____? No, they ____.
A. needn't they; mustn't B. mustn't they; mustn't
C. mustn't they; needn't D. shouldn't they; should