请问肯定祈使句中的反意疑问句，什么时候要用won't / would 或can / can’t you 或 shall we？

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will/would/can/could/shall/should 均是情态助动词 (modal verbs). 当 modal verbs 出现在句子中而需要转换为反意疑问句时, 我们要在句子的末尾添加一个问题标记 (question tag). Question tag 的规则是前肯后否, 或前否后肯.
例子 : - 情态助动词 (modal verbs) 出现在句子中转换为反意疑问.
- Kara can go herself, can't she?
- You should get up early, shouldn't you?
- You wouldn't do that, would you?
- We must help them, mustn't we?

除了上面的普通句子外，要求别人做事的句子称为'祈使句' (imperative). 祈使句没有反意疑问. 因为它是一个请求. 祈使句只有问题标记 (question tag) 在句尾.
问题标记在祈使句中一般情况是 'will you 或 won't you', 例子 : -
- Open the door, will you?
- Don't smoke in this room, will you?
- Come to my party, won't you?
- Have a coffee, will you?
- Don't look at me like that, won't you?

可是，祈使句的问题标记
- will you/ won't you/ can you/ can't you/ would you / could you 在一般的谈话中也可接受. 不用 shall we. 例子 : -
- Come here, will you?
- Open the windows, would you?
- Keep quiet, can't you?
- Shut up, won't you?

一个好的法则是, 祈使句的问题标记在考试中和文书上应该只使用 'will you'.