动词不定式做主语课件-高考英语一轮复习

动词不定式做主语授课：希希Activity1读句感悟阅读下列句子，认真感悟加颜色部分，并完成方框下的小题。(1)However，duringthisperiod，itcanbeeasyforsomeofthemtoformbadhabits.(2)Topreventharmfulhabitslikethesefromdominatingateenager’slifeisessential.(3)Tochangebad

habitsisnevereasy，evenwithmanyattempts.(4)Afterall，itisnoteasytobreakbadhabits.1.以上句子中动词不定式都是作

。2.句(1)和句(4)中it作

，真正的主语是后面的

。主语形式主语动词不定式Activity2语法精析一、基本用法动词不定式作主语时，谓语动词用单数。Tolookafterthesenaughtyboysisreallydifficult.照看这些淘气的男孩真的很难。为了避免头重脚轻，常用it作形式主语放在句首，作主语的不定式常置于句末。Itwouldbebetterforyoutogothere.你还是去那里的好。ObserveandDiscover1.Itisn’trighttotalklikethat.

2.It’sdifficulttomasterEnglish.3.It’shardformetoanswerthequestion.4.Itisbettertohavelovedandlostthannevertohavelovedatall.以上四个句子有两点共同之处：1.句子的真正主语都是____________，但都使用it作形式主语；2.句子的表语都是______。动词不定式形容词it+be+adj+(逻辑主语)+todosthObservation4Discover4ObserveandDiscover动词不定式的逻辑主语常用__________来表示，当形容词修饰动词不定式时，此时常用介词_____。当表语形容词表示不定式的逻辑主语的性质或特征时，则用介词____。1.Itisn’trightforustostophalfway.

=Tostophalfwayisnotright.2.It’skindofyoutothinksomuchofus.

=Youarekindtothinksomuchofus.for/of+sbforofObservation5Discover5It’sveryeasyforhimtoworkoutthismathproblem.对他来说解出这道数学题很容易。Itwascarelessofhimtomakesuchamistake.＝Hewascarelesstomakesuchamistake.犯了这样的错误，他太粗心了。二、动词不定式和动名词作主语的异同点1.动名词和不定式作主语的相同点(1)不定式和动名词作主语时，常常为了保持句子的平衡，用it来作形式主语，如：

ItisnoteasytolearnEnglishwell.学好英语不容易。Itisnouseaskinghimforhelp.向他求助是没有用的。(2)如果主语用了不定式，表语和宾语也要用不定式；主语用了动名词，表语和宾语也要用动名词，这在英语中称为对称性，如：Toseeistobelieve.＝Seeingisbelieving.眼见为实。Itisbettertostayhomethantogoout.待在家里比出去要好。ObserveandDiscover1.Toseeisto

believe.2.To

do

this

isto

cut

the

foot

to

fit

the

shoe.3.To

say

isonethingandto

do

isanother.4.To

make

a

detailed

plan

isagoodideatomakeitsuccessful.Observation12.动名词和不定式作主语的不同点(1)不定式作主语常表示具体的某一动作；表示泛指或一般的抽象的概念时，多用动名词。Walkingisagoodformofexerciseforboththeyoungandtheold.散步是一种老少皆宜的很好的运动形式。Furtherthinking1.______(do)morningexercisesregularlyisgoodforyourhealth.

2.Itfeelsreallygood______(do)morningexercisestoday.DoingtodoCompletethefollowingsentencesandcomparetheirusages.(2)在“It＋be＋nouse(good/help/need等)”之后常用动名词作主语，而少用不定式。Itisnousecryingoverthesplitmilk.覆水难收。Itisnohelptakingthismedicine.服用这种药没有用。注意：如果该句型中用了for引出不定式的逻辑主语，就只能用不定式。Itisnogoodforustodothatexercise.我们做那种练习没有好处。(3)不定式可以和when，where，how，what，whether等连用，在句子中作主语、宾语和表语，而动名词则不能。Wheretoputtheboxseemshardtodecide.很难决定把这个箱子放在哪里。Whethertodoithasn’tbeendecided.是否做这件事还没定下来。返回ObserveandDiscover1.Howtousethecomputerisaquestion.2.Wheretoputthebikes

isbeingdiscussed.3.Whenandwheretohavethemeetinghasnotbeendecided.________和动词不定式构成不定式短语作主语。疑问词包括疑问代词who、whom、what、which、whose以及疑问副词when、where和how。此外连接词whether也适用。此时，疑问词+todo结构可以转化为一个________，例如：Howtousethecomputerisaquestion.

=___________________________________________疑问词主语从句Howwecanusethecomputerisaquestion.Observation8Discover8ObserveandDiscover1.Ittookmemorethananhourtodomyhomeworkyesterdayevening.2.It

will

takeusalongtimetowalkthere.3.Howlongdoesittaketogetthere?

4.Howmuchdiditcostyoutosendthepackage?Observation7Discover7以上四个句子是动词不定式作真正主语，由

it作形式主语引导的句子，它们的谓语是_________。它们的共同句式是________________________________________，表示某人花多少时间或金钱做某事。

take/costittakes

(costs)sbsometime

/moneyto do sth课堂练习Ⅰ.翻译句子1.被邀请参加玛丽的生日派对是很荣幸的事情。__________________________________________________________2.我们难以在15分钟内写完这篇作文。____________________________________________________________________________________________________________________3.你把老师说的所有东西都记下来是愚蠢的。__________________________________________________________It’sagreathonourtobeinvitedtoMary’sbirthdayparty.Itisdifficultforustofinishwritingthecompositioninaquarterofanhour.Itisstupidofyoutowritedowneverythingtheteachersays.4.爱与被爱是一个人所能寻找的最大的幸福。__________________________________________________________5.他不给他们任何东西，这显得太自私了。__________________________________________________________Toloveandtobelovedisthegreatesthappinessonecanseek.Itseemedselfishofhimnottogivethemanything.1.

(英语说得流利)ismydream.Iamcompletelyawarethatitisdifficult2.

(流利地说英语).SoIaskedmyEnglishteacherforhelpstraight

away.Shegavemesomeadvice.Firstofall，itisnecessaryforyou3._________

(在任何可能的时候说英语).Besides，itisveryimportant4.

(练习正确的发音).Allinall，itispossi