主语从句讲解

SubjectClauses

主语从句

定义：用作主语的从句叫主语从句,它是名词性从句之一.Whatitwastobecomewasuncertainuntilbetween4.5and3.8billionyearsagowhenthedustsettledintoasolidglobe.Whatisevenmoreimportantisthatastheearthcooleddown,waterbegantoappearonitssurface.Whatmanyscientistsbelieveisthatthecontinuedpresenceofwaterallowedtheearthtodissolveharmfulgasesandacidintotheoceansandseas.表语主语宾语1)连接代词what

(whatever),

who(whoever)

,which(whichever),whom,whose.Whichsidewillwinisnotclear.Whowillwritethepoemhasnotbeendecidedyet.Whateverhedidisright.Whatthecitywillbestillremainsamystery.连接代词引导主语从句，在句中作主语，宾语，表语，定语。定语主语宾语表语Theearthbecamesoviolentthatitwasnotclearwhethertheshapewouldlastornot.Itwasnotimmediatelyobviousthatwaterwastobefundamentaltothedevelopmentoflife.Sowhetherlifewillcontinueontheearthformillionsofyearstocomewilldependonwhetherthisproblemcanbesolved.从属连词：that，whether引导主语从句只起引导作用，在主语从句中不充当任何成分，that本身无实际意义，但不能省略.whether意为“是否”，放在句首句末皆可。

Thatpricewillgoupiscertain.

Thathewillcomeiscertain.

Whetherwegobytrainorbyboatmakesnodifference.

Whether

he’ll

come

here

isn’t

clear.

Whytheysuddenlydisappearedstillremainsamystery.3)连接副词when，where，how，why等,在从句中做状语。How

this

happened

is

not

clear

to

anyone.

Whenhewillbebackdependsontheweather.Whenwe’llstarttomorrowwillbetoldsoon.Wherethetestwillbegivenisnotyetdecided.总结：引导主语从句的连接词有：从属连词:that,whether；连接代词:who(whoever),whom,whose,what(whatever)和which(whichever)；连接副词:when,where,how和why。Makesentences:It’scertain.we’llbelate.Ishecomingornot？Wedon’tknowWhatdoeshewanttotellus?Wedon’tknowWhenwillyoucomeback?Itdoesn’tmatter.It’scertainthatwewillbelate.Thatwe’llbelateiscertain.Wedon’tknowwhetherheiscomingornot.Whetherheiscomingisnotknown.Wedon’tknowwhathewantstotellus.Whathewantstotellusisnotknown.Whenyouwillcomebackdoesn’tmatter.Itdoesn’tmatterwhenyouwillcomeback.主语从句后置!为了避免主语冗长,句子头重脚轻,经常用it作形式主语,主语从句放在后面作真正的主语.例:

Thatweshallbelateiscertain.--It’scertainthatweshallbelate.1.Thattheearthisroundisknowntoall.--2.Thatyoumissedthechanceisapity.--Itisapitythatyoumissedthechance.It’sknowntoallthattheearthisround.A.

It+be+形容词+that从句(obvious,

true,

surprising,

good,

wonderful,

funny,

possible,

likely,

certain,

probable,

etc.)

如：

It

is

certain

that

she

will

do

well

in

her

exam.

B.

It+be+名词词组+that从句

(an

honour,

a

fact,

a

pity,

etc）如：

It’s

a

pity

that

we

can’t

go.

2.用it作形式主语的结构C.

It+be+过去分词

+that从句

(said,

reported,

thought,

expected,

decided,

announced,

etc。）如：

It

is

said

that

Mr.

Green

has

arrived

in

Beijing.

D.

It+不及物动词或短语+that从句(seem，happen,doesn’t

matter,turnout）

。如：

It

happened

that

I

was

out

that

day.

It

doesn’t

matter

whether

she

will

come

or

not.

1）主语从句在句首时，必须由连接词引导，不能省略这些连接词。误：Theyshouldlikeeachotherisnatural.2)如果主语从句放在句首，不能用if引导，但是如果用it做形式主语，而把主语从句放在句末时，也可以用if引导.误：IfMaryreallyheardhimisreallydoubtful.注意正：Thattheyshouldlikeeachotherisnatural.

Itisnaturalthattheyshouldlikeeachother.正：WhetherMaryreallyheardhimisreallydoubtful.ItwasdoubtfulifMaryreallyheardhim.Whatyouleftareonlyseveraloldbooks.Whatyousaidisofgreatimportance.3）主语从句中用陈述语序4）主谓一致主句谓语一般用单数形式。1.“what”和“who”引导主语从句时，谓语动词的数与主句中作表语的名词一致。Howhesucceededisstillapuzzle.2.如果and连接两个或者两个以上的主语从句作主语时，谓语动词用复数；由两个或多个连接词引导一个主语从句时，谓语动词用单数。Whentheywillstartandwheretheywillgo____notbeendecidedyet.Whenandwherethemeetingwillbeheld____notbeendecided.havehas5).用于Itisimportant/natural/necessary/impossiblethat...句型中,主语从句应使用虚拟语气,用“should+动词原形”的形式,should有时可以省略。6).在It+be+suggested/advised/ordered/requested/insisted/required中,that从句的谓语也应该用“should+动词原形”的形式,should有时可以省略。1.Whereshallwespendtheholidayisn’tdecided.2.Youhavemadeamistakeisafact.3.Thatiscertainthatwecanwin.4.Nomatterwholeavestheroomlastoughttoturnoffthelights.5.Ifthepolicemenwillcomeisnotcertain.weshallThatyouhaveItisWhoeverwhether改错练习6.Itissaythathewasafamouswriter.7.Itisseemedthatitisgoingtorainsoon.8.Thatisfactthatshewonthefirstplace.9.Wholeavestheroomlastoughttoturnoffthelights.10.Itisimportantthatastudentlearnsaforeignlanguage.saidseemsItisafactWhoevershouldlearn___hemadeanimportantspeechatthemeetingwastrue.

A.ThatB.WhyC.WhatD.How

2.___we’llgocampingtomorrowdependsontheweather.AIfBWhetherCThatDWhere

3.___isknowntousallthatAmericaisadevelopedcountry.AWhichBAsCWhatDIt4.It’sknowntousall___aformofenergy.A.waterisB.thatwateris