2024届高三英语二轮复习：状语从句语法课件(共80张PPT)

(共80张PPT)
状语从句
在复合句中作状语的句子叫状语从句。状语从句在主从复合句中修饰主句中的动词、形容词、副词或整个主句。按意义可分为时间、地点、原因、目的、结果、条件、方式、比较、让步等状语从句。状语从句可放在句首，也可放在句末。放在句首时，从句后面常用一个逗号；放在句末时，从句前一般不用逗号。
状语从句
when/while
用表示时间的连词连接一个句子作状语，这样的主从复合句就是时间状语从句。连接时间状语从句的连接词有：when, before, after, while, as soon as, until, since等
一、时间状语从句
1.when
when引导的时间状语从句时表示“当……的时候”，when既可以指时间段也可指时间点，从句中既可用延续性动词又可用瞬间性动词，且动作既可和主句的动作同时发生又可在主句的动作之前或之后发生。且when引导的时间状语从句中一般用一般现在时表将来（主将从现）。
I will call you when I get there. 我到那的时候会给你打电话的。
When I came home my wife was cooking dinner.当我回家的时候我的妻子在做晚饭。
When I got to the airport，the guests had left.
当我到达机场时，客人已经离开。
练一练
雨停了我就回家。
I will go home when the rain stops.
一、时间状语从句
1.when
注意
（1）如果when引导的时间状语从句的主语与主句主语相同，而从句的谓语又是be动词时，那么从句中的主语和be可以省略。
When (you are) in trouble, ask her for help.
当你遇到困难时，找她帮忙

（2）当when引导的时间状语从句的主语与主句主语相同时，往往还可以省略从句的主语并用“when+分词”的形式替代该状语从句。
When I came into the room (=When coming into the room), I found him lying there asleep.
当我走进房间，我发现他躺在那里睡着了。
一、时间状语从句
2.while
while引导时间状语从句时表示“当……的时候”，它强调主句的动作与从句的动作同时持续地进行，用于这一用法时while引导的时间状语从句和主句中的谓语动词必须是延续性动词，或者强调主句的动作发生在从句动作的进行过程中，此时主句中的谓语动词通常是非延续性动词。记住，从句中始终是延续性动词，且从句多用进行时态。（while还可以表示对比，译成“然而”，放在句首可以表示“虽然”）
I met her while I was at school.我在学校时遇见她了。
Study while you study; play while you play.该学就学，该玩就玩。
练一练
外面在下雨时我们在做作业。
We were doing our homework while it was raining outside.
一、时间状语从句
1.as
特别提示 : when, while , as 辨析
（1）as, when引导短暂性动作的动词。
Just as/Just when/When I stopped my car, a man came up to me.
我刹车后，有一个人向我走来。

（2）当从句的动作发生于主句动作之前，只能用when引导这个从句，不可用as或while。
When you have finished your work, you may have a rest.
干完活后，你可以休息一下。

（3）从句表示“随时间推移”连词能用as，不用when或while。
As the day went on, the weather got worse.
日子一天天过去，天气越变越坏。
一、时间状语从句
2.before/after
（1）before引导时间状语从句时表示主句的动作发生在从句动作之前,常翻译为在“……之前”，“……才……”或“……就……”。
Turn off the lights before you go to bed. 睡觉前要关灯。

Before he went to university he was a worker. 上大学之前他是工人。

（2）after引导时间状语从句时表示主句的动作发生在从句动作之后
I will tell you after they leave.
他们走我再告诉你。

After you finish the letter show it to me．
信写完后给我看看。
一、时间状语从句
until/till/since
1.until/till until/till表示“直到……”。

He waited until she was about to leave. 他等着一直到她准备离开。

I watched him until he disappeared in the distance. 我瞧着他直到他在远处消失。

这类句型的主句动词通常只能是延续性动词，不能是终止性动词。但是，在否定句中，主句动词可以是终止性动词，此时构成not…until/till…句式，意为“直到……才……”。
She didn't marry until she was over fifty. 她直到五十多岁才结婚。

We'd better not go until your sister arrives.
我们最好等你姐姐到了再走。
一、时间状语从句
2.since
since引导的时间状语从句表示“自从……以来”
（1）引导时间状语从句时，一般指的是“从过去的某一时间点以来”的概念，表示动作从过去一直持续到现在。从句用一般过去时，主句用完成时。
I have never seen him again since he left here.
自从他离开那里之后我就再也没有见到他了。

They have been friends ever since they were in school.
他们从上学开始就是朋友了。

练一练
他来到这就没有说过话。
He hasn’t spoken since he got here.
一、时间状语从句
2.since
since引导的时间状语从句表示“自从……以来”
（2）若表示到过去某一时间前的情况，则主句用过去时，从句用过去完成时。 通搭配为it was+时间段+since 过去完成时或it is+时间段+since过去时。
It is four years since my sister lived in Beijing. 我妹妹不在北京住有四年了。

It was three years since we had been there.我们在那已经有三年了。

（3）延续性动词相反翻译，瞬间性动词正常翻译
It is three years since I smoked a cigar.我不抽烟三年了。

It is three years since I left there.我离开那里已经三年了。
一、时间状语从句
as soon as/by the time
1.as soon as等
表示“一……就”

I will go there directly I have finished my breakfast.
吃完早饭，我立即到那里去。

The moment I heard the news, I hastened to the spot.
我一听到消息，马上赶到了出事地点。

As soon as I reach Canada, I will ring you up.
我一到加拿大，就给你来电话。
一、时间状语从句
1.as soon as等,表示“一……就”
特别提示
hardly(scarcely, rarely)…when/before, no sooner…than相当于as soon as之意。主句用过去完成时，从句用一般过去时。当hardly, scarcely, rarely和no sooner位于句首时，主句应用倒装语序。
He had no sooner arrived home than he was asked to start on another journey.
他刚到家，就被邀请开始另一旅程。

No sooner had the sun shown itself above the horizon than he got out of bed to commence work.太阳刚从地平线上升起，他就起床劳动去了。

Hardly had I sat down when he stepped in.我刚坐下，他就进来了。

He had hardly fallen asleep when he felt a soft touch on his shoulder.
这个阿拉伯人刚要入睡就感到肩膀上被轻轻一触。
一、时间状语从句
1.as soon as等,表示“一……就”
练一练
他让你一回到家就给他回电话。
He asked you to call him back as soon as you got home.
我刚入睡就被孩子们的吵闹声吵醒了。
I was awakened by the noise of the children as soon as I fell asleep.
或
No sooner had I fallen asleep than I was awakened by the noise of the children.
一、时间状语从句
2.by the time
在一般情况下，如果从句的谓语动词用一般过去时，主句的谓语动词用过去完成时；如果从句的谓语动词用一般现在时，主句的谓语动词用将来完成时。

By the time you came back, I had finished this book.
到你回来时，我已经写完这本书了。

By the time you come here tomorrow, I will have finished this work.
你明天来这儿的时候，我将已经完成此工作了。
练一练
等你到这，他也要离开了。
By the time you get here, he will be gone.
一、时间状语从句
each time/as long as
1.each time, every time等
表示“每次”“每当”

Each time he came to Harbin, he would call on me.
他每次来哈尔滨，总是来看我。

Whenever that man says “To tell the truth”, I suspect that he's about to tell a lie.
每当那个人说“说实在话”的时候，我猜想他就要说谎了。
一、时间状语从句
2.as long as和so long as
这两个连词表示“只要”

You can go where you like as long as you get back before dark.
你可以随意到哪里去，只要在天黑以前回来就行。

I will fight against these conditions as long as there is a breath in my body!
只要我一息尚存，我就要反对这种境况！

You grow younger every time I see you.
每次遇到你，见你更年轻了。
一、时间状语从句
地点状语从句表示地点、方位，通常由where，wherever等引导。

We must camp where we can get water.我们必须在能找到水的地方露营。

1.where在地点状语从句中，除指地点外，还可指处境等。

He said he was happy where he was. 他说他对自己的处境很满意。

2.有时地点状语从句中的某些词可以省略。

Fill in the blanks with the given phrases. Change the form where necessary.
用所给的短语填空，必要的地方可以改变其形式。
二、地点状语从句（一）
3.地点状语从句一般置于主句之后。

Keep it where you can see it.
把它放在你看得见的地方。

注意：根据强调的需要，anywhere, everywhere和wherever也可以 (where则一般不可以) 放在句首。
二、地点状语从句（一）
1.where一般表示一个确定的但非特指的地点。
The church was built where there had once been a Roman temple.
教堂建在曾一度是罗马神庙的地方。
2.wherever, anywhere和everywhere 表示“任何地方”。
I will find you wherever you are. 无论你在哪儿，我都会找到你。
I always remind of you everywhere we have stayed together.
在我们曾经待过的每一处，我总是能想起你。
You can go anywhere you want to go.
你可以去任何你想去的地方。练习都能帮你提高。
二、地点状语从句（二）
because
because引导的原因状语从句一般放于主句的后面，because从句位于句首时要用逗号分开，放在句末时，可不用逗号分开。because表示直接原因，语气最强，最适合回答why引导的疑问句。

I do it because I like it.
我做这件事是因为我喜欢。

You can trust those products because the quality never varies.
你可以信赖那些产品，因为它们的质量从来不变。

We went by bus because it was cheaper.
我们乘公交汽车去，因为这样便宜一些。
三、原因状语从句
because
注意：“not...because”结构中的not否定的是because引导的整个从句。
误：The country is not strong because it is large.
正：The country is strong not just because it is large.
国强不在大。

I didn't help him, not because I was unwilling, but because I was unable to do it.
我没有帮助他，不是因为我不愿意，而是因为我力不从心。
三、原因状语从句
since
since引导的时间状语从句一般放于主句之前表示已知的、显然的理由(通常被翻译成“既然”)，较为正式，语气比because弱。

Since you are free today, you had better help me with my mathematics.
既然今天你休息，你最好帮我补习数学。

Since you don't trust him, you should not employ him.
你既然不信任他，你就不该雇用他。
三、原因状语从句
since
注意：seeing (that)，now (that)，considering (that)，in that这几个词汇与since引导的原因状语从句意思相近， 都表示“既然”。

Seeing (that) he refused to help us, there's no reason that we should now help him.他既然曾经拒绝帮助我们， 我们没有理由要来帮助他。

Now (that) you are grown up, you should not rely on your parents.
既然你长大了， 就不应该依靠你的父母了。

Considering (that) everybody is here, let's begin our discussion.
既然大家都到了， 我们就开始讨论吧。

In that he is ill, he feels unable to do it.因为他生病了，他觉得做不了那件事。
三、原因状语从句
as
as引导原因状语从句时表示附带说明的“双方已知的原因”，语气比since弱，较为正式，位置较为灵活(常放于主句之前)。

As it is raining, you'd better take a taxi.
既然在下雨，你最好乘出租汽车。

As you are tired, you had better rest.
既然累了，你最好休息一下。

I went to bed early, as I was exhausted.
我睡得早，因为我已筋疲力尽了。
三、原因状语从句
for
for引导的是并列句表示原因但并不说明主句行为发生的直接原因，只提供一些辅助性的补充说明，for引导的并列句只能放于主句之后并且必须用逗号将其与主句隔开。

He could not have seen me, for I was not there.
他不可能见过我，因为我不在那里。

He seldom goes out now, for he is very old.
他难得出门了，因为他年事已高。
三、原因状语从句
for
注意：
1.in view of the fact that可用as/since/seeing that来表示，但不能用because
As/Since/Seeing that you are gere，you may as well give me a hand.
既然你在这里，你就帮我个忙吧。

As/Since/Seeing that Tom knows French, he'd better do the talking.
既然汤姆懂法语，最好让他来谈。
三、原因状语从句
2.在as/since/seeing that意指以前共知的或共知的陈述时，可用if来代替
As/Since/Seeing/If you don't like Bill. Why did you invite him
既然/如果你不喜欢比尔，你为什么邀请了他？
三、原因状语从句
目的状语从句是表示行为目的的从句。引导目的状语从句的主要连词有that, so，so that, so...that, in order that等，从句中常常使用一些情态动词，如can, could, may, might, should等。

that, so that，in order that表示为了，以便，一般放在主句之后。that语气较弱，用的较少，多用so that。

Let's take the front seats that we may se more clearly.我们坐前排吧，这样我们可以看得更清楚些。

Man does not live that he may eat, but eats that he may live.
人生存不是为了吃饭，而吃饭是为了生存。

They hurried so that they might not miss the train.他们为了不误火车，才急急忙忙的。

In order that everyone present might hear her clearly, she raised her voice again.
为了使在场的每个人都能听清楚，她再次提高了声音。
四、地点状语从句（一）
注意：
当主从句的主语一致时，so that和in order that引导的目的状语从句可以转换成相对应的动词不定式结构。

We got up early so that we would arrive in time.
为了能及时赶到，我们起得很早。

They hurried so that they might not miss the train.
→They hurried so as not to miss the train.
他们为了不误火车，才急急忙忙的。

Betty saved money in order that she could uy a portable computer.
→Betty saved money in order to buy a portable computer.
贝蒂存钱是为了买一台手提电脑。
四、地点状语从句（一）
in case, lest, for fear that几个短语都表示万一，惟恐，含有否定的意义。

Better take more clothes in case the weather is cold.
最好多带些衣服以防天气会冷。

Take an umbrella in caseit rains.
以防下雨，带把伞。
四、地点状语从句（二）
so
结果状语从句的从句部分是补充说明主句中谓语动词发生的结果的，通常位于主句之后。

so, that, so that
这三个词都可以引导结果状语从句。so that最为常用，so或that常用于口语或非正式文体中。

What has happened that you look so worried.
发生了什幺事，使你显得如此担心？

I didn't plan the work well, so that so I didn't finish it in time.
我没把工作计划好，结果没按时完成。（so that从句常用逗号与主句隔开）

The room was packed with people, so that we couldn't get in.
房间里挤满了人，我们进不去。
五、结果状语从句
so...that
so...that 如此……以致……
其引导的果状语从句有如下几种结构：

1.so+形容词副词+that-从句
The village is so small that it cannot be shown in the map.
这村子太小，所以这地图上没有。

The wind was so strong that we could hardly move forward.
风刮得那么大，我们简直寸步难行。
五、结果状语从句
2.so+形容词+a/an+单数名词+that-从句
It was so hot a day that tey all went swimming.
天是那么的热以致他们都去游泳了。

He made so inspiring a speech that everybody got excited.
他发表了如此鼓舞人的演讲以致大家都很激动。

3.so+many/few+复数名词+that-从句
I have had so many falls that I am black and blue all over.
我摔了许多跤，以至于浑身青一块，紫一块。

He has so few friend that he often feels lonely.
他朋友很少，所以经常感到孤独。
五、结果状语从句
4.so+much/little+不可数名词+that-从句
I had so little money then that I couldn't even afford a used car.
我当时囊中羞涩，甚至连一辆二手车都买不起。

He drank so much wine last night that he felt terrible.
昨晚他喝了那么多的酒，他觉得很不舒服。

5.在so+形容词/副词+that-从句结构中，如将so+形容词/副词位于句首，主谓语要倒装。
So excited was he that she could not say a word.
他很激动，一句话都说不出来。

So loudly did he speak that even the people in the next room could hear him.
他说得很响，连隔壁的人都能听见。
五、结果状语从句
such...that such...that 如此……以致……
其引导的结果语从句有如下几种结构：

1.such+a/an+形容词+单数可数名词+that-从句
Jenny is such a clever girl that all of us like her very much.
詹妮是如此聪明的女孩，以至我们都非常喜欢她。

We left in such a hurry that we forgot to lock the door.我们走得匆忙，把门都忘了锁了。

2.such+形容词+复数名词+that-从句
He gave suchimportant reasons that he was excused.他说出了这么重要的理由，得到大家的谅解。

They are such interesting novels that all of us want to read them.
这些是十分有意思的小说，大家都想看。
五、结果状语从句
such...that such...that 如此……以致……
其引导的结果语从句有如下几种结构：
3.such+形容词+不可数名词+that-从句
He made such rapid progress that the teacher praised him.他的进步很快，老师表扬了他。

He shut the window with such force that the glass broke.
他关窗子用了那么大的劲，玻璃都碎了。

提示：such+a/an+形容词+单数名词结构可以和so+形容词+a/an+单数名词结构互换。
He told us such a funny story that we all laughed.
→He told us so funny a story that we all laughed.他给我们讲了一个如此有趣的故事，大家都笑。

→The story he told us was so funny that we all laughed.他给我们讲的故事是如此有趣，大家都笑了。
五、结果状语从句
such that
such that可以连用，意思是（是）这样...以致。
Mother's answer was such that she didn't say yes and she didn't say no.
妈妈的回答就是这样，既没有同意也没有不同意。

His anger was such that he lost control of himself.
他勃大怒，以致不能自制。
五、结果状语从句
比较：
such...that...引导的是结果状语从句
such...as...引导的是定语从句

She had such a fright that she fainted.
她吓得昏了过去。

Luckily such earthquakes as can cause a lot of damage do no happen very often.
很幸运，这种破坏性很大的地震并不经常发生。
（关系代词as在定语从句中作主语）
五、结果状语从句
if
条件状语从句是表示主句动作发生的前提或条件的从句。条件状语从句分为真实条件状语从句和非真实条件状语从句。
引导条件状语从句的有if, unless, so as long as, as so far as, on condition that, in case, suppose, supposing等。
条件状语从句中的谓语动词一般要用现在时或过去时代替一般将来时或过去将来时。
六、条件状语从句
if
if表示正面条件，意为如果。

If you ask him, he will help you.
如果你向他请求，他会帮助你。

Difficulties are nothing if we are not afraid of them.
如果我们不怕困难，困难就算不了什么了。

If I do not understand what he says, I always ask him.
我不懂他的话时, 总是去问他。（if = when）
六、条件状语从句
比较：
if only和only if的对比
if only 解释但愿，要是...就好了，表示一个不可能实现愿望，要用虚拟语气。
only if 解释只有，等于only on condition that，从句用陈述语气。

Only if you heat ice, it turns to water.
只有当你给冰加热，它才会变成水。

If only I knew!
要是我知道该多好。
六、条件状语从句
unless
unless=if not, 表示反面条件，意思是如果不、除非。
They will go tomorrow unless it rains.
除非明天下雨，否则他们会去的。
（They will go tomorrow if it doesn't rain.）
I won't let you in unless you show me your pass.
如果你不出示通行证，我就不让你进来。
（=I won't let you in if you don't show me your pass. ）
六、条件状语从句
注意：
if...not和unless通常是可以换用的。但在下列情况下，两者是有区别的：
1.unless多引导真实条件句，if not可以引导真实条件句或非真实条件句。
He won't be able to pass the final exams unless he works hard.
除非他努力，否则就通过不了期末考试。

He won't be able to pass the final exams if he doesn't work hard.
如果他不努力，就通过不了期末考试。

He would pass the final exams if he worked hard.
要是他努力的话，他就会通过考试。（非真实条件句。含义是He doesn't work hard.）
六、条件状语从句
2.如果主句描述的是情感或情绪活动方面的内容，if not结构不能换成unless。
I'll be quite glad if she doesn't come this evening.
她今晚如果不来我很高兴。

3.unless引导的状语从句可用否定结构，而if not引导的从句不可再用否定结构。
Don't ask me to explain again unless you really don't understand.
不要再叫我解释了，除非你真的不懂。

4.uless能作为介词使用，相当于except，而if not不可以。
Nothing will come out of it unless disaster.
这种事除非引起灾祸之外不会有什么结果。
六、条件状语从句
so long as
so long as, as long as, on condition that
这几个短语意思差不多，都表示只要，条件是……。

As/So long as we don't lose heart, we'll find a way to overcome the difficulty.
只要我们不灰心，我们就能找到克服困难的方法。

You may use the room on condition that so long as you clean it afterwards.
只要你用完后打扫干净，你就可以使用这个房间。
六、条件状语从句
in case
in case既引导目的状语从句，也可以引导条件状语从句，等于if it happens that。

In case I forget, please remind me of my promise.
如果我忘了，请提醒我所做的承诺。

Send s a message in case you have any difficulty.
万一你有什么困难，请给我们一个信儿。
六、条件状语从句
providing
providing, provided that, supposing, suppose that, given that
这几个短语意思相近，有如果，只要，假如等意思。

Given that they are inexperienced, they've done a good job.
考虑到他们缺乏经验，他们的工作已做得很好了。(that可以省略)

Provided/Providing（that）we invite him, he would surely come to dinner.
假如我们邀请他的话，他肯定会来吃饭的。

Suppose/Supposing we can't get enough food, what shall we do
假设我们弄不到足够的食物，那我们怎幺办？（仅用于疑问句）
六、条件状语从句
although
让步状语从句表示在某种相反的条件下，主句中的情况依然会出现。让步状语从句由although, though, however, whatever, whoever, whomever, whichever, whenever, wherever, whether（是否）, no matter (who, what, etc.), even if, even though等词引导。

1.although, though
这两个词意思一样，都解释虽然，尽管。although比though正式。

（1）although指事实，多用于句首。多数情况下可与though换用。
Although he is young, he is very clever.他尽管年轻，但很聪明。

Although his illness had prevented him from studying, he managed to pas the exam.
尽管病情妨碍了他学习，但他还是通过了考试。

It was an exciting game, although no goals were scored.
那是一场精彩的球赛，尽管一个球都没进。（although也可放在主句之后）
七、让步状语从句
（2）though既指事实，又指设想。可用于句首、句中或句末。
Though he is poor, he is happy.
他虽然穷，但很快乐。

I haven't checked the information yet, though I think it is correct.
我还没有核实这份资料，但我认为它错不了。

My house, though it is large, is also made of stone and wood.
我的房子虽然大，但是也是用石头和木料搭成的。

提示：
有时though=and yet但是，然而，放在句子末尾，前面用逗号。
It was hard work; I enjoyed it, though.
那工作很苦，但是我喜欢干。
（=It was hard work, but I enjoyed it.）
七、让步状语从句
（3）though从句有时可以倒装，将从句中的一部分提置句首。
Child though he is, he knows a lot.
尽管他是个孩子，他懂得的东西却很多。
（=Although he is a child, he knows a lot.）

Strange though it may look, it is true.
尽管看起来奇怪，但是却是真的。
(= Though it looks strange, it is true.)

注意：
although, though不能与ut连用，但是可以与yet, still, nevertheless连用。
Although Though he blames me, yet I will trust him.尽管他责怪我，但我还是愿意信任他。

Though he was hungry, still he would not eat.尽管他饿了，但是他仍然不想吃。
七、让步状语从句
2.even if, even though
这两个词语气比though, although强，解释即使，两者可以通用。

We won't be discourged even if though we fail ten times.
我们就是失败十次也不泄气。

Even if though you fail, you will have gained experience.
纵然你失败，你也会得到一些经验。
七、让步状语从句
3.as
连词as，同though一样，也可以引导让步状语从句，但从句中要用特殊语序。

Young as he is, he knows a lot.
他虽然年轻，但懂得很多。(= Though he is young,)

Cold as it is, the children play outdoors.
虽然天气冷，但孩子们仍在户外玩。
七、让步状语从句
while
while, where as这两个词也可引导让步状语从句，突出主句和从句的对比。

While I understand what you say, I can't agree with you.
虽然我理解你的意思，但我还是不同意。

Some people like fat meat, whereas others hate it.
有些人喜欢肥肉，相反有些人讨厌肥肉。
七、让步状语从句
no matter
1.no matter (who, what, where, when, etc)
这几个词引导的让步状语从句语气十分强烈。

This is not true, no matter who says so.
不管谁这么说，都不对。

Do it no matter what others say.
不管别人怎么说，尽管干。

No matter how bus he was, he studied English every day.
不管他多忙，他都每天坚持学习英语。
七、让步状语从句
2.however, whatever, whenever, wherever
这些词在意思上和用法上都等于no matter how what

Whatever happens may happen, we shall never lose hope.
无论发生什么，我们都不要失去信心。（有时从句中的动词与may连用）

However (=No matter how) expesive it may be, I'll take it.
无论它有多贵，我也要买下它。

Don't let them in, whoever (=no matter who) they are.
不管他们是谁，别让他们进来。
七、让步状语从句
whether...or (not) ...
whether...or (not) ...意思是不管……还是……。

Whether you believe it or not, it's true.
不管你信不信，这是真的。

Whether the weather is good orbad, they will set off as planned.
不管天气是好还是坏，他们都要按计划启程。

提示：
也可直接用or来连接两个相同结构来表示让步。
Walking or sleeping, she always has the question in her mind.
无论走路还是睡觉，她总是想着这个问题。
七、让步状语从句
if
if有时也可用于让步状语从句，相当于even if

If he is poor, he is at least honest.
尽管他穷，但至少他很诚实。

We'll go if it rains.
即使下雨我们也要去。

I'll do it if I die in the attempt.
即使会丧命我也要试一下。
七、让步状语从句
注意：
有些时间、地点、条件、方式或让步等状语从句中，如果谓语含有动词be，主语又和主句中的主语一致，或者主语是it，常把从句中的主语和谓语的一部分（特别是动词be）省略掉。
Look out for cars when crossing the stret.过街时当心车辆。
(=when you are crossing the street)

She hurriedly left the room as though angry.她急匆匆地走出屋去，好象很生气的样子。
（=as thoughif she was were angry)

If possible, I'd like to have two copies of it.可能的话，我想要两本。
（=if it is possible,)

She advised me not to say anything unless asked.她劝我别说什么，除非有人要我说。
（=unless I was asked )

As a young man, he studied law and became a lawyer.他年轻时就学了法律，并当了律师。
（=As When he was a young man,）
as...as
比较状语从句主要运用于形容词和副词的原级、比较级及最高级的句子之中。

原级：as…as（和……一样），not so（as）…as …（和不一样）
比较级：more…than（更）
最高级：The most…in/of， the+形容词+est…of/in
八、比较状语从句
as...as, the same as
用于同等程度级的比较。否定句用not so/as...as, not the same...as

Our country is as big as the whole of Europe.
我们的国同整个欧洲一样大。

The result was not asso good as I had expected.
结果不如我预料的那么好。

She works in the same building as my sister.
她和我的妹妹在同一大楼上班。
八、比较状语从句
than
than表示不同程度级的比较

It rains mor often in Shanghai than in Beijing.上海下的雨比北京的多。

He is two inches taller than his father.
= He is taller than his father by two inches.他比他爸爸高两英寸。

注意：
在比较从句中通常把和主句重复的部分省掉，如果把省略部分补上，而显得累赘或不合乎习惯。
Lily isn't so clever a girl as Lucy is.莉莉是一个不如露西那样聪明的女孩。
（如说成：Lily isn't so clever a girl as Lucy is clever.显得累赘）

The child sang as sweetly as a nightingale.这孩子歌唱得同夜莺般婉转。
八、比较状语从句
the more...the more...
the more..., the more...这是表示比例的比较，意思是越……就越……。第一个the more也可以看成是一个条件。

The more you read, the better you understand.
你看的书越多，你懂得就越多。
（= If you read more, you will understand better.）

The busier he is, the happier he feels.
他越忙越开心。

The more difficult the questions are, the less likely I am to be able to answer them.
问题越困难，我就越可能回答。
八、比较状语从句
as
方式状语从句是描述动作方式的从句。方式状语从句常由as, as if as though等词引导，通常位于句尾，有时位于句中。

as, just as
这两个连词的意思是如……，正如……一样。just as 比as 语气要强一些。

Do in Rome as the Romans do.入乡随俗。

Leave things as they are.让一切顺其自然。

Please do as you are told.
请按照人家告诉你做的去做。（也可说Please do as told.）

Balloons float in the air just as boats do on the sea.
气球在空中就如同船浮在海面上一样。
九、方式状语从句
注意：
在口语中，还可用like来代替as，引导一个方式状语从句。
She is doing the work exactly like I want her to.
她正在完全按照我要她的那样在做这项工作。

Do you make bread like you make cakes
你做面包的方法是不是和做点心一样？
九、方式状语从句
as if
as if, as though
由as if 或as though引导的状语从句可以用陈述语气表示可能符合事实的情况，也可以用虚拟语气的过去式表示现在不符的或与事实相反的情况（见虚拟语气章节）。

She looks as if she is ill.
看上去她好象是生病了。

The boy plays piano as though he has a natural ear for music.
这孩子弹起钢琴来家好象天生很懂音乐似的。

They talked loudly as if nobody were around.
他们大声说话仿佛周围没人似的。

He acted as ifthough nothing had happened.
他装得似乎什么事也未发生过。
九、方式状语从句
条件
有时为了使语言的精炼，达到言简意赅的效果, 我们常将状语从句进行“简化”。

1.状语从句同时具备下列两个条件:
（1）主句和从句的主语一致，或从句主语为it；
（2）从句主要动词是be的某种形式。从句中的主语和be动词常可省略。
十、状语从句的省略
条件
2.存在于5种从句（比方时条让）
（1）由if，unless等引导的条件状语从句
If (it is) possible, he will help you out of the difficulty.如果可能的话，他会帮你摆脱困境。

You must attend the meeting unless it is inconvenient to you.
除非情况对你来说不方便,否则你必须出席这次会议。

（2）由 although/though, even if/even though等引导的让步状语从句
I won't go to the party even if (I am) invited.即使被邀请我也不会参加这个派对。
（3）由when, while, as, until/till等引导的时间状语从句
While (I was) waiting for him, I found my wallet was missing.
当我正在等他的时候，我发现我的我包丢了。
十、状语从句的省略
条件
注意:
before和after不用于这种情况，要么是连词后面跟句子，要么是介词后面跟名词性成分。
Before you are operated on, you mustn't eat anything.
在你动手术之前，你什么都不能吃。

可说成 Before being operated on, you mustn't eat anything.

不能说 Before operated on, you mustn't eat anything.
十、状语从句的省略
条件
（4）由as, as if等引导的方式状语从句
The meeting took place as (it was) planned.
会议按照计划进行。

（5）由as，than等引导的比较状语从句
The movie was more interesting than (it was) expected.
这部电影比预想的更有趣。
十、状语从句的省略
常用情形
常用于以下几种情形:
1.连词+形容词
As (he was) young, he learned how to ride a bike.
他小时候就学会了骑自行车。

Work hard when (you are) young, or you'll regret.
少壮不努力,老大徒伤悲。

2.连词+名词
Although (he was) a farmer, now he is a famous director.
尽管他曾是个农民,而现在是位著名的导演了。
十、状语从句的省略
常用情形
3.连词+现在分词
Although (he is) doing his best in maths these days, he has still got no good marks.
尽管近来他一直在学数学,但他仍然没有取得好成绩。

4.连词+过去分词
He won't go there with us unless (he is) invited.
除非受到邀请,否则他不会和我们一道去那里。

The concert was a great success than (it was) expected.
这场音乐会出乎意料地取得了巨大成功。
十、状语从句的省略
常用情形
3.连词+现在分词
Although (he is) doing his best in maths these days, he has still got no good marks.
尽管近来他一直在学数学,但他仍然没有取得好成绩。

4.连词+过去分词
He won't go there with us unless (he is) invited.
除非受到邀请,否则他不会和我们一道去那里。

The concert was a great success than (it was) expected.
这场音乐会出乎意料地取得了巨大成功。
5.连词+不定式
He stood up as if (he were) to say something.当时他站起来好像要说什么。

He wouldn't solve the problem even if (he were) to take charge.
即使他来负责,他也解决不了这个问题。
十、状语从句的省略
常用情形
6.连词+介词短语
She looked anxious as though (she was) in trouble.
她看上去很焦急,好像遇到了麻烦。

He had mastered the English language before (he was) in the USA.
他到美国之前就懂英语了。

注意:
当从句主语和主句主语不一致时,从句部分要么用完全形式,要么用独立主格结构来表达。
When the meeting was over, all the people went out of the meeting-room.
当会议结束时,人们都走出了会议室。
十、状语从句的省略
常用情形
7.连词+副词
While (you are) upstairs, keep the windows closed.
当你在楼上的时候，请关着窗户。
十、状语从句的省略
1. While________ (wait) for the opportunity to get promoted, Henry made every effort ________ (perform) his duty.
2. ________ his Chinese was far from perfect, students and teachers cheered his effort.
3. This six-millimetre-long creature _________ (find) in coastal areas and only bites if ________ (disturb).
4. You can never meet the needs of every customer. Some may prefer light colors ________ others enjoy dark ________.
5. So necessary have I found it ________ (learn) about my kid’s schoolwork ________ I will visit his teachers next week.
练一练
waiting
to perform
While / Though / Although
is found
disturbed
while
ones
to learn
that
6. Once ________(print), this dictionary will be very popular ________ students and teachers.
7. When ________(plan) Encyclopedia Britannica《大英百科》, I had to create a table of contents ________ (base) on the topics of its articles.
8. Sun Yixiao was on his way up________ Tuesday evening after school, ________the lift suddenly came to a stop.
9. When he found himself ______(stick) in the lift, a moment of panic________(follow) before the teenager could find a way out.
10. When ________(start) a business, ________ (locate) is the first thing you should take into account.
练一练
printed
with/among
planning
based
on
when
stuck
followed
starting
location
11. If I ________(be) a man then, I would never________(tell) my Dad I was too old ________ a goodbye kiss.
12. Had they________(know) what was coming next, they might ________(have) second thoughts.
13. I’m only a ________(begin) on this instrument; it will be years________ I’m ready to play for the public, but I’m sure I’ll achieve great fame eventually.
14. She and her family________(hide) away for nearly twenty-five months________ they were discovered.
15. I will forbid you to leave______ you make an apology________ what you have done.
练一练
had been
have told
for
known
have had
beginner
had hidden
before
before
unless
for
16. The thief ran away________(direct) he saw the policeman.
17. So valuable ________ (be) this painting that it is difficult ________ (calculate) what its price would be.
18. The experiment shows that proper amounts of exercise, if________(carry) out regularly, can improve our health.
19. Once you are caught________(cheat), you won’t________(allow) to take a test again.
练一练
directly
to calculate
is
carried
cheating
be allowed
谢谢