·请问,must如何构成反意疑问句?

反意疑问句必须前后一致.若是否定回答,另当别论.如:
Must I be at home?
No, you needn't.
同意楼上的意见。反意疑问句应该是mustn't he?
回答者：joannazpsj - 秀才 二级 12-12 22:17

应该改为
isn't he?

请看详细解释
陈述部分有must 的疑问句，疑问部分根据实际情况而定。
He must be a doctor, isn't he?
You must have studied English for three years, haven't you? / didn't you?
He must have finished it yesterday, didn't he?

must在表"推测"时，根据其推测的情况来确定反意疑问句。
He must be there now, isn't he?
It must be going to rain tomorrow, won't it?

参考资料：http://www.hongen.com/eng/pub/yufac/1305.htm

情态动词 must 的反意疑问句

陈述部分有must，且表示"必须"时，附加疑问句部分用mustn't，`如果表示"必要"则用needn't。
陈述部分中是mustn't表示"禁止"时，附加疑问句部分用must。

陈述部分中的must表示"一定"、"想必"等推测意义时，附加疑问句部分而是根据陈述部分的谓语动词或