Unit+1+Science+and+Scientists+Discover+Useful+Structures+课件-2025-2026学年高中英语人教版选择性必修第二册

人教版选必二Discoverusefulstructures（表语从句的几大问题）

1.概念和定义：表语从句是在复合句中作表语的名词性从句。放在系动词之后，一般结构是“主语+系动词+表语从句”2.可以接表语从句的系动词：be,look,remain,seem，appear，sound，feel，smell等。3.引导词：

（1）that

（2）whether

（3）疑问引导词：

A.疑问代词who(m)/what/which/whose;

B.疑问副词when/how/where/why;

C.疑问代词+everwhoever/whatever/whichever

(4)连词：because;asif/asthough

(1)that(充当连词，不作成分；无词义；陈述事实，不含疑问;不能省略。)

例：Thetruthisthatshelied.（2）whether(充当连词,不作成分；有词义；含有疑问“是否”；不能省略)；if不能引导表语从句。例：Thequestioniswhetherthemeasuresareworthtaking.（3）疑问引导词：

A.疑问代词who(m)/what/which/whose;

B.疑问副词when/how/where/why;

C.疑问代词+everwhoever/whatever/whichever

A:疑问代词Who(m）/what/which/whose：

Who(m）/what/which常用作主语、宾语、表语，what/which/whose还可用作定语；有词义；含有疑问（注意：what表“所…的”时候没有疑问”如：Whatshesaid/knew/did…is….）；不能省略。Who、what的区别：相同点：作主语、宾语、表语;不同点：who指人what指事物，what还可作定语。

Whowillattendthemeetingisnotknown.指人，主语

Who(m)youmentionedsurprisedme.指人，宾语

The

key

question

is

who

the

real

criminalis.指人，表语

Whatmadetheteacherangrywasthathewaslateforclassesagain.指物，主语

Whattheywantmostarereliefsupplies.指物，宾语，不含疑问

Whatcausedtheexplosionremainsamystery.含疑问

Whatpartshewillplayintheprojecthasn’tbeenknown.指物，定语

Who和what作表语的区别：

例1.The

key

question

is

who

the

real

leader

is.

例2.He

is

no

longer

what

he

used

to

be.例1中who在从句中作表语，用于说明主语的身份或特征；例2.中what在从句中作表语，用于表达主语过去的情况或样子，表明主语现在已经发生变化。What和which作定语的区别：

例1：Whattoydoyoulike?(不限定具体玩具，无预设范围，询问未知事物或泛指类别。)

例2：Whichtoydoyouprefer,thisoneorthatone?(在指定玩具中选择)

练习：

1.______partshewillplayintheprojecthasn’tbeenknown.

2.______ideaisthebestmustbetriedinpractice.分析：例1中没有明确的范围，属泛指类别，应填What;

例2中有“thebest”表明是在具体的几个中进行比较、选择，应填Which.

Whose作定语的用法：

Whosebookthisisremainsamystery.表示“谁的”，与what/which的语义不同。B.疑问副词when/how/where/why;

它们在句中主要用作状语，有时也可用作表语。

例1.Hedroveasickchildtohisway.Thatwaswhyhewaslateforworktoday.

例2.

Last

summer

holidayswerewhenshetravelledaroundChinawithherparents.

例3.Withouthissupport,wewouldn’tbewherewearenow.“where”

作表语(2018,北京高考)

例4.What

surprised

us

was

how

he

worked

out

the

problem

in

such

a

short

time.C.疑问代词+ever:whoever/whatever/whichever

它们通常用于引导主语从句、宾语从句，较少用于表语从句。在某些特定的语境中，也可用于引导表语从句。如：

例1.Whathewantstogetiswhateveryouhave.(他想得到的是你所拥有的一切。)

例2.The

problem

is

whatever

we

can

affordtosolve.(问题是我能解决什么就解决什么)

(4)连词：because;asif/asthough

连词because引导的表语从句通常只用于“This/That/Itis/wasbecause…”结构中。当主句的主语是时reason，其后面的表语从句要用that引导，而不能用because。

例1.Itisbecausehewascareless.

例2.ThereasonwhyIdidn’tattendtheconferencewasthatIwastoobusy.连词词组asif/asthough也可引导表语从句：意为“好像，仿佛”，引导的表语从句常跟在系动词(seem,appear,look,taste,sound,feel,smell等)之后。若表语从句所述的是非真实的情况，从句用虚拟语气；若所述的是事实或是极可能发生的情况，从句用陈述语气。

Itsoundsasif/thoughsomebodyisknockingatthedoor.

Itlooksasif/thoughhehadbeentoAmerica.

注意：because和asif/though是连词，在句中不作成分。(5)易混的句式：

A.

This/That/It

is

why+表语从句（表结果），表示“这、那就是……的原因”。

B.This/That/Itisbecause+表语从句（表原因）表示……“这、那是因为”。例1.Maybethat’swhyhegotangrywithme.例2.Ithinkitisbecauseyouaretootired.4.表语从句的虚拟语气：两种特定情况

（1）当主句的主语是表示建议、命令、要求或愿望（order,suggestion,idea,plan,proposal,advice,demand）等含义的名词时；

例1.Oursuggestionisthatyou（should）bethefirsttogo.

（2）当表语从句由“asif”

或“asthough”

引导且表示假设而非事实时。

例1.Itlooksasifhewereangry.(与现在事实相反)

例2.Itseemedasthoughshehadknownthesecret.（与过去事实相反）

练习：用适当的连接词填空1.Thequestionis_________wecanmakegoodpreparationsinsuchashorttime.2.Asafamoussingeroncesaid,lifeis_________happenstoyouwhileyouarebusymakingotherplans.3.Theproblemis_________onelesshourofsleepisnotequaltoanextrahourofachievement.4.Thelibrarywas_________hespenthissparetimeincollege.5.Myworryis________Icanturntoincasethecomputercrashes.whetherwhatthatwherewho(m)6.Researchis________I’mdoingwhenIdon’tknowwhatI’mdoing.7.Thesaddestaspectofliferightnowis________sciencegathersknowledgefasterthansocietygatherswisdom.8.Anexpertcanbe________hasmadeallthemistakesthatcanbemadeinaverynarrowfield.9.Thisappliedscience,whichsavesworkandmakeslifeeasier,bringuslittlehappiness.Thatis___