Period 4 单元语法讲练 不定式 一、不定式的种类和形式 1．种类 不定式有两种。一种是带to的不定式，另一种是不带 to 的不定式。不带to的不定式和动词原形相同。 He wants to become a teacher． 他想成为一名教师。 I can help you remember that thing． 我可以帮助你记住那件事情。 2．形式 一般形式：to do 完成式：to have done 进行式：to be doing 一般式的被动形式：to be done 完成式的被动形式：to have been done 完成进行式：to have been doing 二、不定式的作用 1．不定式作主语 To stop the work now seems impossible． 现在停止工作似乎不可能。 To love and to be loved is the greatest happiness one can seek． 爱与被爱是一个人所能寻求的最大幸福。 [名师点津] 很多时候为了避免头重脚轻的现象，常以it 作为先行词，而把不定式移到句子的后部。 It isn't right to gossip about others． 说别人的闲话是不对的。 It is nice not to be dependent on them． 不依靠他们是好的。 It was a pity to have to go without her． 她没能一起去真是可惜。 2．不定式作宾语 She failed to finish the assignment in time，and she was worried about it． 她没有及时完成任务，对此她感到很担心。 I can't afford to buy a car． 我买不起小汽车。 [名师点津] 动词help可用不带to的不定式作宾语。 Regular exercise will help (to) improve your health． 经常锻炼会有助于改善你的健康。 在特定动词后，不定式可以和疑问词连用作宾语。 I hope you'll advise me what to do． 我希望你给我出主意怎么办好。 I couldn't decide which book to choose． 我决定不了选择哪本书。 3．不定式作定语 (1)可以作后置定语修饰前面的名词 I have a lot of work to do． 我有很多工作要做。 He was the first athlete to get to the finishing line．他是第一个到达终点线的选手。 (2)作定语有时会用到被动形式 You are invited to a party to be given at 7：00 pm，on Dec．5． 邀请你参加将于十二月五日晚上七点举行的晚会。 4．不定式作状语 (1)表示原因 He was delighted to see his old friend again． 他再见到他的老朋友感到很高兴。 She was afraid to go out at night． 她晚上不敢外出。 (2)表示目的 A group of young people got together to discuss this question． 一群年轻人聚集在一起讨论这个问题。 I often read China Daily so as to improve my reading． 我常读《中国日报》以提高我的阅读水平。 (3)表示结果 I rushed to the station，only to find the train had already gone． 我匆忙赶到火车站，却发现火车已经开走了。 The house is large enough to hold two hundred people． 这所房子足够大，可以容纳两百人。 (4)修饰整个句子 To tell you the truth，the film was a great disappointment to me． 说实在的，那部影片使我大为失望。 5．不定式作表语 To learn a language is to use it． 学语言是为了使用语言。 To see is to believe． 眼见为实。 6．不定式作宾语补足语 He didn't allow us to smoke in his room． 他不允许我们在他房间里吸烟。 He made a face and made everybody laugh． 他做了一个鬼脸，使得每个人都笑了。 短文语境填空(根据所学语法知识，在空白处填入适当的词) It's easy 1．to neglect (neglect) both mental and physical health in college．If necessary，adjust 2．to lose(lose)weight．Your high metabolism(新陈代谢) makes it easy 3．to control (control)your weight．Your elevated hormones(荷尔蒙) allow you 4．to build (build)muscle an ... ...
