初中英语语法三：动词不定式

英语专题：动词不定式基本结构：todo;否定式：nottodo;没有人称和数的变化；在句子中不能担当谓语时态上：表示将来发生的动作基本含义：语态上：通常表示主动(tobedone)表目的LastweekendIwenttothelibrary_______somebooksonhowtoprotecttheenvironment.A.toborrowB.borrowC.borrowedD.borrowing动词不定式在句中除不能担当谓语外，可以充当其他任何成分，如主语、表语、宾语、定语和状语等Togetupearlyisagoodhabit.Ishouldliketogowithyou.Wehavemuchworktodo.Hewastooexcitedtosayaword.Toseeistobelieve.用动词不定式作主语时，经常有it作形式主语，代替不定式，放在句子的开头，动词不定式则放在谓语的后面,如：Togetupearlyisagoodhabit.Itisagoodhabittogetupearly.(Forus)ToLearnEnglishwelliseasy.ItiseasyforustolearnEnglishwell.如果两个或两个以上的不定式并列使用，后面的不定式往往省略“to”。例如：Iwantyoutostandbesidemeandholdthebooks.常用不定式作宾语的动词有：afford负担得起agree同意ask要求refuse拒绝choose选择decide决定learn学习expect期望hope希望want想要wish希望fail失败promise答应pretend假装练习:用所给的适当形式填空.1.Mymotherhaspromised________(take)metotheparkthisweekend.2.Ican’tafford________(buy)acar.3.Ihope________(stay)withyou.4.Theteacheraskme________(clean)theclassroom.在hadbetter,wouldrather后面的动词不定式不带“to”,例如：Youhadbetterdoitrightnow.You’dbetternotgotherewiththem.在表示感觉的动词如see,feel,watch,hear等及表示“使役”的动词如make,let,have等后面，动词不定式省去to；在动词help后面,动词不定式可以带to，也不以不带to:Don’tletthechildrenplaywithfire.Wewatchedhimdriveoff.Food,sleepandexercisehelpchildren(to)grow.有些动词，如want,like,wish,hope,try,ask,start,learn,agree,teach,decide,understand等，后面可以接连接代词或连接副词加不定式作宾语。例如：Noonecouldtellmewheretogetthebook.没有人能告诉我哪里能找到这本书。Showuswhattodo.告诉我们应该做什么。Idon'tknowwhethertoanswerhisletter.我不知道要不要给他回信。Thesetwodressarebothbeautiful.Idon’tknowwhichtochoose.这两条裙子都很漂亮，我不知道要选哪一条。不定式的复合结构:forsb.todosth.&ofsb.todosth.例如：It‘sverykindofyoutohelpus.非常感谢你帮助我们。IthinkitnecessaryforustostudyEnglishhard.我认为我们努力学英语是必要的。区分：for后面接的形容词是修饰不定式后面所指的sth,此类形容词有important,necessary,difficult,easy等；而of后的形容词则是修饰主语sb，形容词有kind,nice,polite,clever等练习：Thelessonisnoteasy________themtoread.Itwassilly________youtotrustsuchaman.有些动词既可跟动词原形也可跟V-ing形式或todo:stoptodosth停下手上的事情去干另外一件事情stopdoingsth.停止不再干了Thestudentsstoppedtalkingwhentheteachercamein.Ifyoufeeltired,youmaystoptohavearest.goontodosth.做了一件事情，继续去做另外一件事情goondoingsth.继续去做某事（继续做同一件事）forgettodosth忘记干某事（动作尚未发生）forgetdoingsth忘记干了某事（动作已经发生）Don’tforgettolockthedoorwhenyouleave.Iforgottellinghimthestory.我忘了已经告诉过他这件事了。remembertodosth记得去干某事（动作尚未发生）rememberdoingsth.记得干了某事（动作已经发生）trytodosth.尽力、努力去做某事trydoingsth尝试去做某事例：Hetrytofinishallthehomeworkbeforedinnertime.-Iusuallygotherebytrain.-Whynottrygoingbyboatforachange?--我通常乘火车去那儿。--为什么不换乘船呢?see/find/watch/hearsb.dosth.看见/发现/观看/听见某人做了某事(表全过程，或经常性)see/find/watch/hearsb.doingsth.看见/发现/观看/听见某人正在做某事例：Ioftenseeherreadbooksinthelibrary.Isawherreadingbooksinthelibraryyesterday.练习:用所给的适当形式填空.1.Wewatchedthem________(get)offthebus,__________(cross)thestreetand_________(disappear)amongthepeople.2.Suddenlyweheardsomeone__________(cry)forhelp.Thankyou!