(2)对以must提出的疑问句,如作否定回答时,要用needn‘t或用don’t (doesn‘t) have to (不 必)来回答,而不用mustn’t,因为mustn‘t表示的是“禁止”或“不许可”之意,如: ---- Must we finish the work tomorrow? ---- No, you needn't (don't have to), but you must finish it in three days.