1、但在英语中,常用it作形式主语,真正的主语即动词不定式放在后面。Its wrong to play tricks on other people.Its our duty to keep our environment clean and tidy.规律:动词不定式在句中作主语时,常放在It is +adj.(形容词)+to do sth.或 It is +n.(名词)+to do sth.句型中,it仅作形式主语。2.作宾语常可接动词不定式作宾语的动词有:agree(同意), hope(希望), decide(决定), need(需要), mean(打算), wish(希望), fail(失
2、败), want(想要), begin(开始), would like(想要等。Ask(请求), beg(乞求), leave, like, love, hate(讨厌), prefer(宁愿), order(命令), teach, (教)tell,(告诉) believe(相信), find,(找出) know,(知道) want,(想要) think,(认为) understand,(明白)a.want,decide ,agree等动词后面跟并且只能跟不定式。We agreed to start early. She wants to be a doctor.b.love,like ,be
3、gin,start,hate ,prefer等词后面可以接不定式。上述动词后面除接不定式外,还可以接动名词,意思无很大区别。贴士:like doing指经常性动作,而like to do指一次性的动作。I like swimming,but I dont like to swim now.我喜欢游泳,但我现在不想游。c.stop,forget,remember,go on ,try等词或短语后面可以接不定式。上述动词后面接不定式和接动名词意思大不相同。1) stop to do sth.:停止一件事,去做另一件事。2) stop doing sth.:停止正在做的事。例句:When the t
4、eacher came in,the students stopped talking;when he came out,the students stopped to talk.当老师走进来时,学生们停止说话;当老师走出去时,学生们又开始说话。自己思考:forget,remember,go on,try等词或短语后面接不定式和动名词用法的区别(后续详情见最后的“动名词与不定式的区别”)remember to do 记住要做某事 remember doing 记得曾经做过某事 forget to do忘记要做某事 forget doing 忘记曾经做过某事 stop to do 停下来去做某事
5、 stop doing 停止做某事 go on to do 继续做另一件事 go on doing 继续做原来在做的事d.在find/feel/think+it+adj.+to do sth.句型中,it是形式宾语,真正的宾语是后面的动词不定式。The man downstairs found it difficult to get to sleep. I feel it easy to recite the text.某些动词或短语后面既可以接动词不定式作宾语,又可接动名词作宾语,二者用法上的区别可以通过造句子加以区分,如上stop例句。3.作宾语补足语a.tell,ask,want,ord
6、er,teach,invite,warn,wish,help,get等词后面常接不定式作宾补。I tell him not to go there by bus . Edisons mother taught him to read and write.b.let,make,have,see,hear,feel,watch, notice后面接不带to的不定式作宾补。The boss makes them work 16 hours a day. I heard her sing in the next room.若变成被动语态,在上述结构中,不定式符号to要加上。They are made
7、to work 16 hours a day by the boss. She was heard to sing in the next room.4.作定语:放在被修饰的名词、代词后面如:I have a lot of work to do.The doctor said he could do nothing to help the boy.动词不定式若在句中作定语,常放在被修饰的名词、代词之后。如果动词不定式和前面所修饰的词构成动宾关系,若动词是不及物动词,切记不要忘掉介词。I have a small bedroom to live in. Have you got some pen
8、s to write with?5.表语:放在连系动词be后面His wish is to become a scientist.The first important thing is to save the soldierslives.当务之急是抢救战士们的生命。动词不定式在句中作表语时,通常对连系动词前面的名词进行诠释说明。6.作状语a.目的状语:放在go,come,use,live,in order等词后面。I come to see you.He runs fast in order to get there in time.b.原因状语:放在sorry,glad,surprised
9、, disappointed,excited等词后面。I am glad to see you here. I am sorry to trouble you.c.作结果状语。Some of the apples are hard to reach.The room is large enough to hold 1000 people.7.与what,who,whose,when,where, how等疑问词连用,作宾语、宾语补足语、主语等。I dont know what to do next.(宾语)He taught us how to use the computer.(宾语补足语)
10、s still a question how to get there.(主语)后面跟动词不定式的动词口诀有: 三个希望两答应(wish hope want promis agree)两个要求莫拒绝(ask beg refuse ) 想要明白跟知道(would like understand know ) 教会告诉要相信(teach tell believe ) 找出爱恨区别点(find love hate ) 8、(1)“疑问词 + 动词不定式”结构可以作动词know、think、find out等的宾语。eg: I dont know who to ask. 我真不知道该问谁。(2)“疑问
11、词 + 动词不定式”可以作动词show、teach、ask等后面的直接宾语。 She told me where to find the earphone. 她告诉我什么地方可以找到耳机。9、动词不定式可以作介词的宾语。Autumn harvest is about to start. 秋收即将开始。Im worrying about what to do next. 我正愁下一步该怎么办。10、不定式复合结构作主语时,需注意:(1)Its + 形容词 + for / of + sb + to do sth. 当上面的形容词指的是to do sth的性质时,用介词for。 Its danger
12、ous for children to swim in the river. 孩子在这条河里游泳很危险。(游泳这件事情危险) (2)当上面的形容词指的是sb的性质时,用介词of。这些形容词往往修饰人:good, bad, polite, unkind, kind, nice, clever, right, wrong, careful, carelessIt was careless of you to do that. 你这么做真粗心。(你这个人粗心)11、感官动词hear, see, feel, watch, notice, look at, listen to后面直接跟动词原形, 即常见
13、的形式为: hear sb do sth等感官动词后既可跟动词原形作宾补,也可跟v-ing作宾补,前者表示动作的全部过程已结束;后者表示动作正在进行。 Many people like to watch others play games. 许多人喜欢看别人玩游戏. I saw him come downstairs.我看见他下了楼。(说明他下楼了这件事) I saw him coming downstairs.我看见他在下楼。(说明他下楼时的情景)12、It takes sb some time to do sth.花费某人一段时间干某事. It took me half an hour t
14、o do my homework yesterday.昨天我花了半小时做回家作业. It took Jim an hour and a half to read the book.吉姆花了一个半小时看这本书. *用汉字表述上面的句型为:It + take + 人 + 一段时间 + to do sth. 一段时间形式往往为:fifteen minutes15分钟,an hour一个小时, two days两天, half a month半个月,a year and a half一年半.等等不定式的时态和语态时态语态主动被动一般式to doto be done进行式to be doing完成式to have doneto have been done完成进行式to have been doing1) 现在时:一般现在时表示的动词,有时与谓语动词表示的动作同时发生,有时发生在谓
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