高一英语必修三UNIT4课文详解

HOW

LIFE

BEGAN

ON

THE

EARTH地球上生命的起源UNIT4课文讲解1.No

one

knows

exactly

how

the

earth

began,

as

it

happened

so

long

ago.

没有人确切知道地球是怎样开始形成的，因为在很早很早以前地球就形成了。2.However,

according

to

a

widely

accepted

theory,

the

universe

began

with

a

"Big

Bang"

that

threw

matter

in

all

directions.

然而，一种普遍为人们所接受的理论是：宇宙起源于一次大爆炸，这次大爆炸将物质投射到四面八方。

3.After

that,

atoms

began

to

form

and

combine

to

create

stars

and

other

bodies.

然后，原子开始形成并结合成恒星和其他天体。

Par11.For

several

billion

years

after

the

"Big

Bang",

the

earth

was

still

just

a

cloud

of

dust.

大爆炸后好几十亿年过去了，但地球还只是一团尘埃。2.What

it

was

to

become

was

uncertain

until

between

4.5

and

3.8

billion

years

ago

when

the

dust

settled

into

a

solid

globe.

随后它会变成什么没人能知道，直到38—45亿年前，这团尘埃才慢慢地形成一个固体的球状物。3.The

earth

became

so

violent

that

it

was

not

clear

whether

the

shape

would

last

or

not.

地球（开始）变得激烈动荡，不知道这个固体形状是否会继续存在下去。Par24.It

exploded

loudly

with

fire

and

rock.

They

were

in

time

to

produce

carbon,

nitrogen,

water

vapour

and

other

gases,

which

were

to

make

the

earth's

atmosphere.

它（地球）猛烈地爆炸喷出了烈火与岩石，最终产生了碳，氮气，水蒸气和其他多种气体，从而形成了地球的大气层。5.

What

is

even

more

important

is

that

as

the

earth

cooled

down,

water

began

to

appear

on

its

surface.

更为重要的是，地球冷却了下来，地球的表面就开始出现了水。

1.

Water

had

also

appeared

on

other

planets

like

Mars

but,

unlike

the

earth,

it

had

disappeared

later.

在火星这些其他行星上都出现了水，但和地球不同的是，这些水后来都消失了。2.It

was

not

immediately

obvious

that

water

was

to

be

fundamental

to

the

development

of

life.

水对于生命的发展会起关键作用，这一点在当时并不明显。3.What

many

scientists

believe

is

that

the

continued

presence

of

water

allowed

the

earth

to

dissolve

harmful

gases

and

acids

into

the

oceans

and

seas.

很多科学家相信，由于地球上长期有水存在，使得地球得以把有害气体和酸性物质溶解在海洋里。

4.This

produced

a

chain

reaction,

which

made

it

possible

for

life

to

develop.

这就产生了一系列的反应，使得生命就有可能开始发展了。Par31.Many

millions

of

years

later,

the

first

extremely

small

plants

began

to

appear

on

the

surface

of

the

water.

好几百万年后，水的表面开始出现了极小的植物。2.They

multiplied

and

filled

the

oceans

and

seas

with

oxygen,

which

encouraged

the

later

development

of

early

shellfish

and

all

sorts

of

fish.

他们繁殖起来就使得海洋充满了氧气，这为早期的贝类及其他各种鱼类后来的进化创造了条件。3.Next,

green

plants

began

to

grow

on

land.

They

were

followed

in

time

by

land

animals.

接着，绿色植物开始出现在陆地上。4.Some

were

insects.

Others,

called

amphibians,

were

able

to

live

on

land

as

well

as

in

the

water.

随后，陆地上出现了动物，其中有一些是昆虫，另外一些叫两栖动物，他们既能在陆上生活，也能在水里生存。

Par45.Later

when

the

plants

grew

into

forests,

reptiles

appeared

for

the

first

time.

后来，当植物长成了森林的时候，爬行动物首次出现了。6.They

produced

young

entirely

by

laying

eggs.

他们一般是通过孵蛋而繁衍后代的。7.After

that,

some

huge

animals,

called

dinosaurs,

developed.

再后来一些叫做恐龙的巨型动物出现了。8.They

laid

eggs

too

and

existed

on

the

earth

for

more

than

140

million

years.

他们也生蛋，在地球上生存了一亿四千多万年。

9.However,65

million

years

ago

the

age

of

the

dinosaurs

ended.

然而，六千五百万年前，恐龙时代结束了。10.Why

they

suddenly

disappeared

still

remains

a

mystery.

他们为什么会突然灭绝至今仍是个谜。

11.This

disappearance

made

possible

the

rise

of

mammals

on

the

earth.

恐龙的灭绝使地球上哺乳动物的增多有了可能。12.These

animals

were

different

from

all

life

forms

in

the

past,

because

they

gave

birth

to

young

baby

animals

and

produced

milk

to

feed

them.

这些动物不同于以往所有的生物形态，因为他们能从体内生产出幼仔并给幼仔哺乳。1.Finally

about

2.6

million

years

ago

some

small

clever

animals,

now

with

hands

and

feet,

appeared

and

spread

all

over

the

earth.

最后，大约260万年前，一些小巧聪明，长着手脚的动物出现了，他们散布在地球的各个地方。2.Thus

they

have,

in

their

turn,

become

the

most

important

animals

on

the

planet.

于是，他们接着成为这个行星上最重要的动物。

3.But

they

are

not

looking

after

the

earth

very

well.

然而，他们对地球却不怎么在意，

Par54.They

are

putting

too

much

carbon

dioxide

into

the

atmosphere,

which

prevents

heat

from

escaping

from

the

earth

into

space.

他们把过多的二氧化碳释放到大气层中，这使得地球上的热不能释放到太空中去。5.As

a

result

of

this,

many

scientists

believe

the

earth

may

become

too

hot

to

live

on.

因此，许多科学家相信地球可能会变得太热而不适合生物生存。

6.So

whether

life

will

continue

on

the

earth

for

millions

of

years

to

come

will

depend

on

whether

this

problem

can

be

solved.所以，在未来的数百万年中，生命能否在地球上延续，取决于这个问题能否得到解决。

主语从句一个句子在复合句中充当主语叫主语从句。常用引导词：连接词：that(无词义)whetherThathewillcomeandhelpusiscertain.Whetherwestayornotmakesnodifference.连接代词:

who(ever)whomwhat(ever)which(ever)whoseWhowillgototheenergyconferenceisnotimportant.连接副词：whenwherehowwhy

Whenandwherethetestwillbegivenisnotdecided.1.引导主语从句的连词是不能省略的。

Thattheearthisroundistrue2.That-从句作主语通常用it作先行词，而将that-从句置于句末，例如：

Itistruethattheearthisround.结构：Attention

a.It+be+形容词+that-从句

Itisnecessarythat…有必要……

Itisimportantthat…重要的是……

Itisobviousthat…很明显……b.It+be+p.p.+that-从句

Itisbelievedthat…人们相信……

Itisknowntoallthat…从所周知……

Ithasbeendecidedthat…已决定……

c.It+be+名词+that-从句

Itiscommonknowledgethat……是常识

Itisasurprisethat…令人惊奇的是……

Itisafactthat…事实是……d.It+不及物动词+that-分句

Itappearsthat…似乎……

Ithappensthat…碰巧……

Itoccurredtomethat…

我突然想起……

2.表示“是否”意义时，一般用whether而不用if引导主语从句，

Whether

shewillcomeornotisstillaquestion3.有时可用形式主语it代替主语从句：

e.g.Itisstillaquestionwhethershewillcomeornot.Ithasnotbeendecidedyetwhentheywillstart.4.无论主语从句有多长，一般做单数处理。

e.g.Whenwewillstarthasnotbeendecidedyet..

注意：

以what开始的主语从句如果后面的表语是复数名词，系动词用复数形式。Whathewantstobuyare

threebooksandtwopens.

1.Itisobvioustothestudents____theyshouldgetwellpreparedfortheirfuture.A.asB.whichC.whetherD.that2.____wantstostayinahotelhastopaytheirownway.A.AnyoneB.TheoneC.WhoeverD.Who练一练！

3.Itisnotimmediatelyclear____thefinancialcrisiswillsoonbeover.A.sinceB.what

C.whenD.whether练一练！____leavestheroomlastoughttoturnoffthelights.A.Anyone

B.ThepersonC.Whoever

D.Who_____thesportsmeetwillbehelddependsontheweather.A.WheneverB.IfC.WhetherD.That___isafactthatEnglishisbeingacceptedasaninternationallanguage.A.ThereB.This

C.ThatD.It

宾语从句一个句子在复合句中充当宾语就叫宾语从句连接词：that(无词义)whetherife.g.Idon’tknowwhether(if)youarewillingtohelpme.连接代词：what(ever)who(ever)whosewhich(ever)等连接副词：whenwherehowwhy等特别提示1.由连接词that引导宾语从句时，that在句中不担任任何成分。I’mgladthatyouhavepassedtheexam.2.有些词或词组如hate,love,enjoy,dislike,feellike,appreciate,take(认为),relyon,don’tmind等，习惯上后面跟it做形式宾语，再接宾语从句。Itakeitthatyouwillagreewithus.3.在接复合宾语的句子中，为了保持句子平衡，用it作形式宾语，而将从句放在句尾。常带复合宾语的动词有：make/find/see/hear/feel/think等。I

thinkitnecessarythatItakeplentyofwatereveryday.4.某些动词后的宾语从句常用虚拟语气，如insist，order，request，suggest等。Isuggestedthatwe(should)startbefore5o'clock.5.必须用whether引导，不可用if:1).

从句后有or

not

时，不可用if:Idon’tknowwhetherhewillcomeornot.2).

介词宾语通常用whether引导:Itdependsonwhetherheiscomingornot.3).

后接动词不定式时。Canyoutellmewhethertogoortostay?4).discuss后面的宾语从句解释为是否用whetherImagineyouareinthissituation,anddiscusswhetheryoushoulddosomethingatonce.5)主语从句放在句首Whetherwestayornotmakesnodifference.6）表语从句和同位语从句Thequestioniswhether

wecangetthereontime.7)当it做形式主语whether/if都可引导主语从句Ithasntbeendecidedwhether/ifweshallattendthemeeting.6.用who，whom,which(ever),whose,when,what(ever),where,why,how,whoever等关联词引导的宾语从句相当于特殊疑问句，应注意句子语序要用陈述语序。Doyouknowhowoldheis?Iwanttoknowwhathehastoldyou.Shealwaysthinksofhowshecanworkwell.Shewillgivewhoeverneedshelpawarmsupport.凡需要帮助的人，她都会给予热情的支持。7.think,believe,imagine,suppose等动词引起的否定性宾语从句中，要把上述主句中的动词变为否定式。即将从句中的否定形式移到主句中。例如：

Wedon’tthinkyouarehere.我们认为你不在这。

Idon’tbelievehewilldoso.我相信他不会这样做。

如果主句主语为第一人称反意疑问句常与从句的主语和谓语保持一致；其他情况看主句。例如：

Idon'tbelieveshehasbeentoAustralia,hasshe?我认为她没去澳大利亚，是吗？Idon'tbelievethathecantranslatethisbook,

?Shethinksthatherhusbandisthebestoneintheteam,

？canhedoesn’tsheIdoubtif/whetherhewillpasstheexam.Idon’tdoubt

thatwewillwinthematch.Doyoudoubt

thathediditonhisown?

doubt问题肯定句中用if/whether否定句中用that

疑定句中用that

Idoubt_________heistellingthetruth.Weneverdoubt_________theplanwillbecarriedout.Doeshedoubt_________youarefromAustria?I’mdoubtful_________hewillagreetothis.

if/whether

that

that

if/whether宾语从句中的连接词that在以下三种情况下不能省略：（1）当that从句与另一名词性从句并列作宾语时，第二个that不能省；（2）当that作介词宾语时，that不可省掉。（3）用it做形式宾语的宾语从句Everyoneknewwhathappenedandthatshewasworried.Thereasonliesinthatsheworksharderthantheothersdo.宾语从句Heasked____foraviolin．（MET1992）

A.