must,need,mustn't,needn't的用法?

问题描述:

must,need,mustn't,needn't的用法?

must表示必须、义务等,相当于have to,但must强调主观因素,而have to强调客观因素.I must go to see a doctor.我得看医生去.need可以对MUST引导的一般疑问句作否定回答.Really?Must I go with you?是吗?要我和你一起...