must 的在反意疑问句中怎么用

问题描述:

must 的在反意疑问句中怎么用
详细解释下了谢谢大家了

must如果作“一定”解,表推测的话,反意疑问词用do did is
如:He must have finished his homework,hasn't he?
must如果作“必须”解,反意疑问词用need
如:He must clean the room,needn't he?