“不定式”,即“不一定是什么词性的成分”,可当作名词、形容词和副词来使用。因此不定式在句子中能够充当除谓语之外的其他任何成分。 1). 动词不定式基本构成 注意:动词不定式在一些感官动词(see, watch, hear等)或使役动词(make, let, have等)的后面,做宾补时,通常会省略to,如: The boss made me work ten hours a day. =I was made to work ten hours a day by the boss. 这个老板让我一天工作十个小时。 2). 动词不定式的语法功能:动词不定式在句子中可充当主语、表语、宾语、宾补、定语和状语(即除谓语之外的各种成分)。 (1). 不定式作主语 ①动词不定式短语作句子主语时,视为单数,谓语动词用第三人称单数,如: To make work more efficient is our goal. 让工作更有效率是我们的目标。 ②不定式短语作主语时,为了考虑句子的平衡,常用it作形式主语,而将真正的不定式主语放在句子后面,结构为:It+is/ was+ adj. (+for sb.)+动词不定式,如上一句话也可写成: It’s our goal to make work efficient. 我们的目标是让工作更有效率。 It’s very important for us to learn English well. 学好英语对于我们来说很重要。 (2). 不定式作宾语 ①动词不定式跟在及物动词后作宾语,这种形式非常常见,就是我们平时积累的一些动词后面跟to do形式,如:I have decided to study hard. 我已经决定要刻苦学习。 常见的这类动词有:begin, choose, continue, decide, expect, fail, forget, hate, help, hope, learn, manage, mean, need, offer, plan, prefer, pretend, promise, refuse, try, want, wish, determine, afford, agree, start, like等。 ②在find,think后跟不定式时,常用it代替,而将真正宾语,即不定式放在后面,如:I find it not easy to achieve one’s goal. 我发现实现一个人的目标并不容易。 ③有些不定式结构中的to会省略,直接跟动词原形,这样的结构有:Why not do…, Why don’t you do…, had better (not) do…, would rather do…等,如: I would rather stay at home. 我宁愿待在家里。 (3). 不定式作宾语补足语 ①不定式宾补很常见,结构为:动词+sb. to do sth, 这样的动词有:tell, ask, want, allow, get, would like, encourage等,如: The teacher advised us to have a rest first. 老师建议我们先休息一下。 ②see, hear, watch, notice, have, make, let等动词后作宾补的动词不定式不带to,但变为被动语态以后(即不定式作主补时)要带to,如: My mom made me clean the house. = I was made to clean the house by my mom. 我妈妈让我把房间打扫干净。 注意:help(帮助)后作宾补的动词不定式可带to,也可不带to,即help sb.(to)do sth.,如:He often helps his parents (to) do their housework. 他经常帮助他父母做家务。 (4). 不定式作定语 不定式有时起形容词作用,修饰名词,代词,在句中作定语。不定式作定语位于所修饰的名词,代词之后,如: Who was the first one to get to the top of the hill yesterday? 昨天谁第一个登上了山顶? He is the man to depend on/to believe in. 他是一个值得信赖/相信的人。 (5). 不定式作状语:不定式放在不及物动词后可表目的或原因状语,也可以放在一些形容词后。 ①目的状语:She reads China Daily every day to improve her English. 她每天都读中国日报,来提高自己的英语能力。 ②原因状语:I’m glad to see you. 很高兴见到你。 注:这种“be+形容词+不定式”结构,其不定式有时也可视为宾语,如:He is eager to go to college./ She is sure to come here. ③结果状语:They lived to see the liberation of their hometown. 他们一直活到见到家乡解放。 (6). 疑问词+不定式 不定式可以和疑问代词who,what,which及疑问副词when,how,where连用,构成不定式短语,在句中可作主语、表语或宾语,如: How to finish the work in time is a problem.(主语) 如何按时完成任务是个问题。 We don’t know when and where to go.(宾语) 我们不知道何时出发,也不知道要去哪。 【重难点】 动词不定式中形式主语的使用 在It+is/ was+ adj. for sb. to do的结构中,若形容词为表示人的内在品质,则介词不用for而用of,如:It’s very clever ofyou to do like that. 你那么做真是太聪明了。(正确) It’s very kind foryou to help me. 你能帮我真是太好了。(错误) 【易错点】 1). 使役动词省略to的不定式的被动形式 一些使役动词的不定式中to可省略,被动需还原,如: I was made to finish my homework on time by my teacher.(正确) I was made finishmy homework on time by my teacher.(错误) 老师让我按时完成作业。 2). have sb. do sth.,have sb. doing sth.和have sth. done的区别 (1). have sb. do sth意为“让某人做”,have可用let,make代替,如: The soldier had the boy stand against the wall. 士兵让这个男孩靠墙站着。 (2). have sb. doing sth.表示“使某人做出某种反应”或“保持某种状态”,如: Within minutes he had the whole audience laughing and clapping. 短短几分钟他就令全体观众欢笑,鼓掌。 (3). have sth. done意为“让某事被做”,如: The driver had his car washed once a week. 这个司机一周让人洗一次车。 |
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