单元语法精讲———动词不定式 动词不定式是一种非谓语动词的形式，没有人称和数的变化，不能单独作谓语。其构成形式为：to+动词原形，其中to为不定式符号，本身无实际意义。其否定形式为：to+动词原形。动词不定式具有名词、形容词和副词的特点，可以在句子中作主语、表语、宾语、宾语补足语、状语、定语等。 1．作主语 动词不定式作主语时，谓语动词用单数，当主语过长时，常用it作形式主语，而把真正的主语———动词不定式放到后面。 作表语 动词不定式可以放在系动词后作表语。 3．作宾语 有些动词后面可以接动词不定式作宾语。如：want, like, love, try, hope, remember, decide, agree, stop, hate等。 4．作宾语补足语 动词不定式也可以作宾语补足语，用来补充说明宾语。需要注意的是，作动词ask, invite, want, wish, tell, advise等的宾语补足语时，不定式符号to不可以省略；作使役动词let, have, make以及感官动词see, watch等的宾语补足语时，不定式符号to要省略；作动词help的宾语补足语时，不定式符号to可以省略，也可以不省略。 作状语 动词不定式在句中作状语，表示目的、结果、原因等。 6．作定语 动词不定式作定语时，一般都是作后置定语，修饰前面的名词或代词，不及物动词的不定式作定语时，后面需加上相应的介词。 【拓展】动词不定式也可以与特殊疑问词what, which, how, when, where等连用。 【注意】以下几种情况使用不带to的动词不定式： 1．在固定词组had better之后。如： You had better go home now.你最好现在回家。 2．在引导疑问句的why not之后。如： Why not go with us 为什么不跟我们一起走呢？ 单元语法集训 I．根据句意，用所给动词的适当形式填空。 1．It’s very nice of you _____（help）me with my English and physics. 2．His work is _____（clean）the buildings and to water the flowers every day. 3．The weather is so sunny, we decide _____（take）a walk outside. 4．My mother asked me _____（buy）some bananas. 5．Before the meeting, let me _____（tell）you some interesting news. 6．Could you help me _____（carry）the books to the classroom 7．I often use the Internet _____（send）e-mails to my teachers and friends. 8．It looks like a good place _____（have）a rest. II．单项选择。 ( )1．_____ the piano well, we must have a lot of practice. A．Plays B．To play C．Played D．Play ( )2．Tell the children _____ fast food. It’s bad for their health. A．not to eat B．not eating C．to eat D．eating ( )3．If you are sad, a good laugh will make you _____ better. A．feel B．to feel C．feeling D．felt ( )4．—Don’t forget _____ your homework, Jill. —OK, I’ll do it at once. A．doing B．to do C．did D．do ( )5．It’s too difficult for all of us _____ the work in such a short time. A．finish B．finishing C．finished D．to finish 单元重难点集训 题组训练一 allow的用法 ( )1．My mother doesn’t allow me _____ TV at all. A．to watch B．watching C．watched D．watch ( )2．Schools don’t allow _____ answers in the exam. A．copy B．to copy C．copying D．copied ( )3．—Hello! Would you like to go to the movie with me tonight —Sorry, I can’t. Dad won’t _____ me to go out in the evening. offer B．allow C．ask D．Care 题组训练二 seldom等频度副词的用法 ( )1．Sandy likes travelling. She ___ stays at home during holidays. A．seldom B．usually C．always D．o ... ...
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