must,need,引导的疑问句回答方式有什么不同?

问题描述:

must,need,引导的疑问句回答方式有什么不同?

Must I go off now Yes,you must.No ,you needn't/don't have to.(否定形式mustn't是禁止、不许,所以不用)Need I gave him a hand Yes,you must/should.( 情态动词need不用于肯定句中)No,you needn't....