新概念英语第二册lesson17-18 - 图文 下载本文

?Key structure

在其他时态时,must的有些含义可以用have to或havegot to。这三种形式一般可以互换,但用于第一人称时,have to(have got to)强调客观的要求或外在的原因,must 则强调主观的要求或表示说话的人认为自己有权做某事。

have to和have got to往往可以互换,但与always,sometimes 等频度副词连用时,用have to往往比用havt got to好。have got to比have to更口语化。

?????????Key structure

在过去时的句子中可以有任意时态

, 要用have to 来表示“必须”,have toShe will have to… to…

;She had to… ;She has/I have had have toto;didn't have to

作为实义动词, 否定式为don't have to;will not have 在表达“难道你不能不(做you…?”,而不用“Do you have to…?……)”时,一般用“”

Must Must you leave now? 难道你非得现在就走吗?I’m afraid so. I have to study for an exam.

mustdone可以表示推测,表示对过去的推测must do表示对现在的推测;must have He must be mad.

在说成I think…/he thinks…“I think he must be a fool.的从句中,一定要用事实说话”)

. (不能???Key structure

的否定式为can’t be(不可能):’s using the phone, it must be John.’t be John. He promised me he wouldn’t must beSomeoneIt canuse it today.

Special Difficulties

As的用法

①作为介词,可以表示“作为”、“以……身份”等In this film, he appeared as a policeman.

As a mechanic, he can’t always keep himself clean.

②作为连词,可以表示“因为”、“正当……时候”、“以……方或“如同……那样”等

You must take care of the bady tomorrow as I am going to London(因为,由于)

As we were talking about him, he knocked at the door.(正当……时候)

Do as you are told. 叫你怎么做就怎么做(按你被告知的那样去做)(以……方式)

As I learned, … (如同……那样)③“担任……工作”I work as an engineer.