主語從句定義：在句子中作主語的從句叫做主語從句，按照引導詞分為以下幾種:連接詞that:引導的從句一般位于句首，that在從句中不作任何成分，沒有實際意義，只有連接作用。Thathewillcometothepartyhasexcitedeveryone.有時用it作形式主語，把從句后置,常見的結構有：It’s+形容詞(obvious,true,surprising,good,wonderful,possible...)+that從句

Itiscertainthatshewilldowellinherexam.毫無疑問她\t"/1270/18/_blank"考試成績會很好。

Itisprobablethathetoldhereverything.很可能他把一切都告訴她了。

It’s+名詞詞組(afact,anhonour,agoodthing,apity,nosurprise...)+that從句

It'sapitythatwecan'tgo.很遺憾我們不能去。

It'sanhonourthatourteamwinthegame.我們贏得這場比賽真榮幸。

It’s+過去分詞(said,reported,expected,decided,announced...)+that從句

ItissaidthatMr.greenhasarrivedinbeijing.據(jù)說格林先生已經(jīng)到了北京。

Itisreportedthatcoralreefsarebeingdestroyed.據(jù)報道珊瑚礁正遭受破壞。It+seems/happens等不及物動詞+that從句。

ItseemsthatAliceisnotcomingtothepartyatall.Alice似乎不來參加晚會。

IthappenedthatIwasoutthatday.碰巧我那天外出了。

2、if/whether:表示是否，在從句中不作任何成分，whether引導從句時可位于句首句末，但是if引導從句時只能用it作形式主語，從句后置。Whethertheworkcanbefinishedontimeisdoubtful.Itisdoubtfulif/whethertheworkcanbefinishedontime連接代詞&連接副詞連接代詞what/who/which/whose/whatever/whoever/whichever等；連接副詞when/where/why/how等，在從句充當一定的成分。Whowilljoinushasnotbeendecided誰將加入我們還沒被決定。Whathelikesmostisplayingcomputergames.他最喜歡的是玩游戲。Whenthenewroadisopenhasnotbeendecided.新道路什么時候開通還沒決定。Whoeverwantstosuccessshouldworkhard.無論是誰想成功必須努力工作。表語從句定義：在句子中作表語的從句叫做主語從句，按照引導詞分為以下幾種:連接詞1、that在從句中不作任何成分，只有連接作用。Thefactisthathedoesn’treallytry.

ThetroubleisthatIhavelosthisaddress.

whether是否（if不能引導表語從句）Thequestioniswhetherthefilmisworthseeing.asif/asthough好像，仿佛Itlooksasifitisgoingtorain.because因為Iamsleepy,anditisbecauseIstayeduplatelastnight.連接代詞&連接副詞連接代詞what/who/whom/which/whose/whatever/whoever/whichever等；連接副詞when/where/why/how等，在從句充當一定的成分。ThisiswhatIaminterestedin.Thedoubtiswhohastakenawaythedocument.Thatwaswherewecampedlasttime.Thequestionishowwecandotheworkbetter.注意點：1、當主句主語為reason時，表語從句引導詞需要用that，而不是why/because.Thereasonfortheaccidentisthatthedriverwasdrunk.事故的原因是司機酒駕。當主句主語是advice/suggestion/request/order等表示命令建議的名詞時，從句的謂語常用：(should)+動詞原形形式。Myadviceisthatwe(should)haveadiscussionaboutthismatter.同位語從句定義：同位語從句時用以解釋、說明某一名詞的內容的從句，在句子的作用等同于前面的名詞?？梢愿徽Z從句的名詞通常有news，idea，fact，promise，question，doubt，advice，hope，message，suggestion，words，possibility,decision等。連接詞that連接作用，沒有實際意義Thefactthatsomecountriesarestillsufferingpovertyisreallyabigproblem.whether“是否”（if不能引導同位語從句）Thereissomedoubtwhetherhewillcome.連接代詞&連接副詞連接代詞what/who/whom等（which不能引導同位語從句），在從句中充當一定成分。Ihavenoideawhatsizeshoesshewears.Thequestionwhowilltakehisplaceisstillnotclear.連接副詞when/where/how/why等，在從句中充當一定成分。Wehaven’tyetsettledthequestionwherewearegoingtospendourvacation.Thequestionwhymanypeoplechoosetoliveinthecountrysideisunderdiscussion.判斷技巧判斷從句所在位置：主語從句位于句首或者it作形式主語的句末；表語從句位于系動詞后面；同位語位于常見的名詞后面（news、idea等，起到解釋說明作用）。判斷從句缺少的成分以及句子的意思：缺少主語、賓語、表語、定語，考慮連接代詞；缺少狀語，考慮連接副詞；不缺少成分，考慮that/if/whether。習題_______youcomeornotwillnotmakeanydifference.WhetherB.ThatC.IfItissaid_______Mikewillcometomorrow.whetherB.thatC.whyItissurprising______myparentsgavemesuchagoodgift.thatB.whenC.if______willwinfirstprizeisuncertain.ThatB.WhoC.Where______wewillvisitShanghaimakesmeveryhappy.ThatB.WhetherC.When______causedtheaccidentremainsunknown.WhereB.WhenC.What______thishappenedisnotcleartoanyoneWhoB.HowC.What______dinosaursdiedoutremainsapuzzle.WhoB.WhatC.WhyThereasonwhyhefailedis______hewastoocareless.thatB.becauseC.whenIwaslateforclassthismorning.Thatis____mybikebrokedownonthewaytoschool.thatB.becauseC.whyThetroubleis_____Ihavelosthisaddress.thatB.whenC.whoThequestionis_____wegetthere,7:00or7:30.whetherB.whenC.whoItsounds_____youarefromthesouthoftheUS.asifB.whenC.who_____wantstobeamemberoftheteammustobeytherules.WheneverB.WhoeverC.WhatGrandmapointedtothehospitalandsaid,“Thatis_____Iwasborn.”whereB.whenC.becauseThefact_____sheworkshardiswellknowntous.thatB.howC.whetherHekepthispromise____hewouldalwaysdoanythingtomakesureofherhappinessthatB.whenC.whether18、Ihavesmalldoubt______heissuitableforthejob.A.thatB.whoC.whether19、Ihavenoidea______heisdoingnow.A.thatB.whatC.when補充合適的引導詞。Heexcitedlypulledhardatit,and__________hesawmadehimshout,“Wow!Abig,shinygoldchain!”whatExpertssaythat__________isneedediscontinuousattentionandmaintenance.whatProblemis__________istoblame,parents,studentsorothermembersofsociety.whoTheidea__________humansownadeepbiologicalneedtoconnectwithnaturehasbeencalled“Biophilia”thatThemostpleasantthingoftherainyseasonis

________onecanbeentirelyfreefromdust.thatThemanagerputforwardasuggestion_______weshouldhaveanassistant.Thereistoomuchworktodo.that

________weunderstandthingshasalottodowithwhatwefeel.HowExactly______thepotatowasintroducedintoEuropeisuncertain,butitwasprobablyaround1565.whenItisoftenthecase_______anythingispossibleforthosewhohang