一、从句的分类

名词性从句：主语从句、宾语从句、表语从句、同位语从句
定语从句(形容词从句)
状语从句(副词从句)

二、定语从句

在句子中充当定语的成分，所以叫做定语从句，同时这类从句对某个人或事物进行描述，具有形容词的性质，所以也被称作”形容词从句”。

1、定语从句的思维方式

中文思维：这兔子在吃一根我买来的胡萝卜
英文思维：这兔子在吃一根胡萝卜[胡萝卜的关系词]我买。
The rabbit is eating a carrot that I bought.
that I bought做定语从句修饰胡萝卜。

中文思维一般都是将定语前置，而因英文思维如果定语是一个句子则习惯性后置，例如：

一根好吃的胡萝卜(中)
a tasty carrot(英)

一根兔子吃了的胡萝卜(中)
a carrot that the rabbit ate(英)

一个是兔子的老师(中)
a teacher who is a rabbit(英)

一个我昨天看见的老师(中)
a teacher whom I saw yesterday(英)

兔子吃胡萝卜的地方 (中)
the palce where the rabbit ate the carrot(英)

兔子吃胡萝卜的原因(中)
the reason why the rabbit ate carrot(英)

有时候，如果定语很长，虽然中文思维形式同一，但是中文思维定语可能太长了，说了半天才说了啥，比如：一只几个月前开始在B站上传视频专门教人英语的讨人喜爱的兔子。而英语就直接说明要描述啥然后加上关系词再慢慢描述：This is a rabbit who started uploading videos since a few months ago to focus on English teaching and is liked by many students.

注：上面这种太长了句子最好拆成几句，不然理解起来太费劲了。

2、定语从句的构成

先行词
关系词：关系代词和关系副词

关系代词

关系代词引导的形容词(定语)从句

The rabbit is eating a carrot that I bought.
The teacher who ate a carrot is a rabbit
The teacher whom I saw yesterday is a rabbit.
The teacher whose favorite food is carrot is a rabbit.
The food which the teacher likes is a carrot.

上面的引导词that、who、whom、whose、which的词性是代词，所以是关系代词。
关系代词代指前面的先行词The rabbit、The teacher、The food。

that vs. which

关系代词that和which经常可以互换

先行词是唯一的：that
先行词多选一：which

例如：
The rabbit ate the largest carrot that I’ve ever seen.
…all the rabbits that ate a carrot
…the only the rabbits that ate a carrot
…the first the rabbits that ate a carrot

The rabbit ate a carrot which I bought.
当然这里的which也可以用that
The rabbit ate a carrot that I bought.

关系副词

关系代词引导的形容词(定语)从句

This was the place where the rabbit ate the carrot.
This is the reason why the rabbit ate the carrot.
That was the day when the rabbit ate the carrot for the first time.

上面的引导词where、why、when的词性是副词不是代词所以是关系副词。
关系副词代指前面的先行词the place、the reason、the day。

上面的关系副词也可以转变为关系代词来表示，比如：
This was the place at which the rabbit ate the carrot.
This is the reason for which the rabbit ate the carrot.
That was the day on which the rabbit ate the carrot for the first time.

关系副词 = 介词+which

3、定语从句的限定性和非限定性

限定性

限定范围
The rabbit ate the carrot which was on the table.
吃的是放在桌子上的那一根。

限定了carrot的范围/性质。

这种定语从句叫做限定性定语从句

非限定性

简单理解，就是没有限定作用的从句
The rabbit ate the carrot， which was on the table.
兔子吃了胡萝卜，胡萝卜是放在桌子上的。which压根没有限定作用，只是单纯的用一个代词which继续说话而已。相当于
The rabbit ate the carrot. The carrot was on the table.

再比如：

I have a head which is round.我有好几个头，其中一个是圆的
I have a head,which is round.我有一个头，这个头是圆的

非限定性形容词从句作插入语

就是因为这种非限定性的形容词从句没有限定作用，只是起着”接着补充”继续说的效果，所以非限定性形容词从句作插入语.

My head,which is big, is useful when it rains.
我有大头，下雨不愁.

The biggest carrot, which the rabbit ate,was on the table.
最大的那根胡萝卜，曾经在桌上，兔子吃了它。

非限定性形容词从句指代整句话

非限定性形容词从句不一定是指代某个先行词，而是可以指代整句话。

The rabbit ate carrot, which was not surpring.

这里的which指代兔子吃胡萝卜这件事~

三、名词性从句

名词性从句包括：主语从句、宾语从句、表语(主语补语)从句、同位语从句、宾语补语从句(比较少介绍)

1、主语从句

The fact is obvious.这事实是明显的.这里的主语是The fact
我们只需要把主语和前面的定冠词the换成一个从句就变成了主语从句
That the rabbit ate a carrot is obvious.

说白了，主语从句就是句子的主语由从句充当。

引导词

比如上面的，我们靠引导词that来表明”That the rabbit ate a carrot”是一个从句。
中文是没有引导词的概念的，但是英美人士只要看到that会下意思的意识到这只是一个从句，只是整个句子的一部分而已…

再举几个例子

Whether the rabbit ate the carrot is obvious.
Where the rabbit ate the carrot is obvious.
When the rabbit ate the carrot is obvious.
How the rabbit ate the carrot is obvious.
Who ate the carrot is obvious.
What the rabbit ate the carrot is obvious.

上面的Whether、Where、When、How、Who、What都是主语从句的引导词.
引导词再主语从句中属于”连接代词/连接副词”,但是再疑问句中就属于”疑问代词/疑问副词”

形式主语

比如下面的一句话
That the hungry rabbit had already eaten a carrot for dinner this evening is obvious.

感觉前面的主语从句太长了，说了半天才知道说啥,头重脚轻的。英美人士习惯性改一下形式，如下
It is obvious that the hungry rabbit had already eaten a carrot for dinner this evening.

这里的it本身没有实际意义，指代了后面的 that the hungry rabbit had already eaten a carrot for dinner this evening主语从句，所以叫做”形式主语”.

It is obvious that the rabbit ate a carrot.

上面的
Whether the rabbit ate the carrot is obvious.
Where the rabbit ate the carrot is obvious.
When the rabbit ate the carrot is obvious.
How the rabbit ate the carrot is obvious.
Who ate the carrot is obvious.
What the rabbit ate the carrot is obvious.

都可以改为形式主语的模式。
It is obvious whether the rabbit ate the carrot.
It is obvious where the rabbit ate the carrot.
It is obvious when the rabbit ate the carrot.
It is obvious how the rabbit ate the carrot.
It is obvious who ate the carrot.
It is obvious what the rabbit ate the carrot.

2、宾语从句

宾语从句其实就是从句在整个复杂句中做宾语而已。

I saw that the rabbit ate a carrot.
其中 that the rabbit ate a carrot.就是一个宾语从句.

上面是确定的信息，不确定的信息也可以做宾语从句
I saw whether the rabbit ate the carrot.
I saw who ate the carrot.
I saw what the rabbit ate.
I saw where the rabbit ate the carrot.
I saw when the rabbit ate the carrot.
I saw how the rabbit ate the carrot.

正常情况下，从句的引导词都会从句的开头：whether、who、what、where、when、how。

宾语从句的引导词that往往可以省略

I know that the rabbit ate a carrot.
可以直接说
I know the rabbit ate a carrot.

宾语从句只有that引导词可以省略，其它引导词不可以省略。

宾语从句的引导词that有时候不可以省略

比如由两个宾语从句的不能省略
I didn’t know that the rabbit ate the carrot and that you saw it.

有插入语的情况下也不能神略

I know，just like you do,that the rabbit ate the carrot.

否定加在谓语动词前，而非从句中

I don’t think (that) the rabbit is smart.
I don’t believe (that) you will give me some coins.
I don’t except(that) you will give this video a thumbs-up.

主从时态一致

大多数情况下，宾语从句和主句中的时态要保持一致

I don’t think (that) you’re right
主句和从句都是现在。

I knew (that) the rabbit liked carrots.
主句和从句都是过去。

只有不变的客观的现象才是例外，比如：
I knew (that) the sun rises in the east.

be+形容词+that…

I am sure that there’s a carrot on the table.

上面的句型归类有争议：宾语从句？同位语从句？状语从句？

这里将上面的句型归类于宾语从句是因为这类句子的形容词往往表达某种看法或者判断，而从句也相当于某种看法或者判断…

比如上面的中文表达为：我确信….。所以后面的从句有点类似动作的承受者(虽然有点牵强)

总之，上面的句型还没有一个定论，看个人喜好，我偏向于”宾语从句”…

3、表语从句

也可以叫做主语补语从句，因为往往后面的表语是补充说明主语的，比如
I am a teacher.
The carrot tastes good.

我们知道在系动词之后的成分做句子中的表语，所以表语从句就是用一个从句充当表语.

表语从句中最常见的系动词就是be动词

The problem is that the rabbit is hungry.
The reason is that there’s no more carrot.
The question is whether the rabbit is hungry.
The question is what the rabbit should eat.
The question is where/when/how the rabbit should eat the carrot.

还有非be动词的系动词

It seems that the rabbit is hungry.
It feels that you’re not telling the truth.

seem
v. 似乎; (涉及推断)好像; 看来; (用以缓和语气)感到好像; (表示不确切或客气)看来好像;

feel
v. 感觉; 觉得; 体会到; (通过触觉)注意到; 感觉到(抽象事物);

系动词的分类

类别	系动词
be动词	am,is,are
感官	look,sound,taste,smell,feel
状态	keep,stay,remain,stand,lie
变化	get,become,grow,turn,go,come,fall
显得	appear,seem
终止	prove,turn out

状态：
keep healthy
stay calm
remain silent
stand empty
lie idle

remain
v. 保持; 仍然是; 剩余; 遗留; 继续存在; 仍需去做(或说、处理);

变化：
get + 天气变化,get colder/ warmer
turn：颜色变化,When spring comes, leaves turn green.
grow：强调渐变的过程,grow old/ dark/ impatient
go：从好变坏,go mad/ bad/ deaf/ wrong 疯了/（食物）坏了/ 聋了/ 出毛病了
come：从坏变好,Your dream will come true.你的梦想会成真的。
fall：陷入某种状态,fall ill/ sick 生病

显得：
seem，appear “显得、好像”
两者都适用于下面这种结构：
seem/ appear to do sth.= It seems/ appears that…

The lady seems to be nice.= It seems that the lady is nice.

终止：
prove “证明是……”
prove (to be) + adj.
What I said proves to be right!

prove (to be) + n.
Betty proves to be a funny teacher.

prove that…
Yu has tried so hard to prove that he is not a loser.

turn out “结果是……”
turn out to be + adj.
The news turned out to be false.

It turns out that…
It turned out that the news was false.
那消息后来证明是假的。

4、同位语从句

同位语就是用不同的方式把一个概念再说一遍，用逗号隔开

My teacher,Papa Rabbit,likes carrots.
I like my teacher,Papa Rabbit.

Papa Rabbit是同位语，跟My teacher表达的是同一个概念。

当我们用一个从句来表示同位语时，就是同位语从句。
这样的从句常在句中修饰抽象的名词，因为抽奖，所以才需要用”另一种方式再说一遍”…
例如：
The fact that the rabbit ate the carrot dit not surprise me.

当然还有其它引导词
The question whether the rabbit will eat the carrot is on all our minds.
I have no idea who ate the carrot.
I am sure of the fact that there’s a carrot on the table.

5、冷门从句：宾语补语从句

就是用一个从句充当句子的宾补。
My education made me who I am today.

四、副词从句（状语从句）

在句子中起到副词的作用，一般补充说明动词，形容词，副词等，充当句子成分的状语，所以也叫状语从句。

作状语，在句子成分在有多种可能，所以副词从句很多！

副词从句的分类

我们可以根据用途或者意义，把副词从句分为如下九类
1、表时间（如：在…之前）
2、表地点（如：在…地方）
3、表条件（如：如果…）
4、表让步（如：虽然…但是）
5、表方式（如：就好像…）
6、表比较（如：比…）
7、表原因（如：因为…所以…）
8、表目的（如：为了…）
9、表结果（如：所以…）

1、时间状语从句

before、when、while、as、after、since、until、as soon as、the next time

在某一时间点之前

…..O…T……

引导词：before

The rabbit ate a carrot at home before the wolf stopped by.
大灰狼串门之前，兔子吃了根胡萝卜.

上面是主句在从句之前，我们也可以把从句放到主句的前面
before the wolf stopped by,the rabbit ate a carrot at home .

此时为了便于断句，需要在从句后加上逗号。

在某一时间点之中(当时)

引导词：when，while，as

The rabbit was eating a carrot when I reached home.
我到家的时候，兔子在吃胡萝卜.

The rabbit was eating a carrot while I was making a video.
我做视频的过程中，兔子再吃胡萝卜

I ate carrot as I made the video.
我一边吃胡萝卜一边做视频。

When、While、As之间的区别
1、When：时间点，”突然”
O
………T…….
When一般强调某个时间点，比如当我回到家的那个时候，有”突然”之意。

The rabbit was eating a carrot at home when the wolf stopped by.
兔子在家吃胡萝卜的时候（突然）大灰狼来串门了。

The rabbit was about to eat a carrot at home when the wolf stopped by.
兔子在家刚要吃胡萝卜的时候，（突然）大灰狼来串门了。

2、While：时间段
OOOOO
……TTTTT…..

While一般强调一个时间段内.

The rabbit was eating a carrot while I was making a video.
我做视频的过程中，兔子再吃胡萝卜

3、As：同时
As一般强调同时进行的两个动作.

I ate carrot as I made the video.
我一边吃胡萝卜一边做视频。

在某一时间点之后

…..T….O…..

引导词：after

The rabbit ate a carrot after the wolf stoped by.
大灰狼串过门之后，兔子吃了根胡萝卜.

从之前某一时间点开始算

…..TOOOOOOOOOO…

引导词：since

这里是指从某时间点算起的时间段，往往暗示了对之后有影响，这样的情况下一般要使用完成状态.

The rabbit has shared three carrots since the wolf stopped by.
自从大灰狼来串门，兔子已经分享了三根胡萝卜了.

The rabbit has not stopped sharing carrots since the wolf stopped by.
自从大灰狼来串门，兔子就一直在分享胡萝卜.

直到之后某一时间点

…..OOOOOT……..

引导词：until

跟since刚好对立，比如

The rabbit waited until the wolf stopped by.
兔子一直在等，直到大灰狼来串门。

The rabbit didn’t eat any carrot until the wolf stopped by.
兔子直到大灰狼来串门才吃了胡萝卜.

一…就….

……TO……

引导词： as soon as

相当于一个动作紧跟着另一个动作发生

The rabbit will eat a carrot as soon as the wolf leaves.

大灰狼一离开兔子就要吃一个胡萝卜.

下次

引导词：the next time

The rabbit will share the biggest carrot the next time the wolf stops by.

下次大灰狼来串门，兔子一定会一起分享最大胡萝卜.

2、地点状语从句

The rabbit ate the carrot where he found it
兔子在找到胡萝卜的地方吃了它

where he found it 为引导词where引导的地点状语从句。

地点状语从句引导词where的强调形式

wherever：不管哪里
everywhere：任何地方
anywhere：所有地方

eg:
The rabbit will go wherever he can find a carrot.
The rabbit sees a carrot everywhere he gose.强调所有地方
The rabbit can eat a carrot anywhere he likes.强调任何地方

3、比较状语从句

英语形容词：比较级
smart，smarter （聪明，更聪明）
big，bigger（大，更大）
beatiful，more beautiful（漂亮，更漂亮）

He is smarter than me.
This carrot is bigger than that one.
She is as beautiful as Snow White.

其实上面的三个句子都是比较状语从句的省略，完整的应该如下
He is smarter than I am.
This carrot is bigger than that one is.
She is more beautiful than Snow White is.

上面的都是用that表示”更…”
也可以用as表示”同样的…”
He is as smart as I am.
This carrot is sa big as that one is.
She is as beautiful as Snow White is.

还有一种用”the(比较级),the(比较级)”表示”越..越…”
The more you practice English,the more fluent you become.
你越多练习英语，你就越流利

用”比较”的方式对前面的主语进行补充说明.

4、条件状语从句

If the rabbit sees a carrot,he will eat it

主将从现

主句将来时态，从句现在时态

因为条件从句一般都表示没有确定的信息，所以没有时间信息，表示一般的默认的普通的，所以通常用一般现在时态，但是在这个条件成立的情况下，主句一定会明确地去做某些动作，所以是比较确定去做的，用将来时态。

总的来说，条件句总是比主句落后一个时间段。比如

If I saw a carrot,I would eat it.
If I had seen a carrot,I would have eaten it.

虚拟语气的过去式saw并不是在表达时间，二十表达与现实相反的条件。

除了if还有引导词unless（除非），比如
用If
If you like this video,you will give it a thumbs-up.

反过来说
If you don’t like this video,you will not give it a thumbs-up.

这句话也可以用unless来说
Unless you like this video,you will not give it a thumbs-up.

除了if和unless，还有其它引导词，比如provided，as long as,in case.

Provided that my video is excellent,you will give it a thumbs-up.
如果我的视频很棒，你会给它点赞。

As longs as I make excellent videos,you will remain my follower.
只要我一直做高质量视频，你就会继续关注我。

In case you don’t understand,please comment below.
如果你不明白，请在下方评论。

5、让步状语从句

含有，即使…也…的意思
Event if see a carrot,I will not eat it.
即使我看到了一根胡萝卜，我也不会吃它。

让步的情况不一定是假设，而可能就是事实。
Although I see a carrot,I will not eat it.
尽管我看到了一根胡萝卜，但我不会吃它.

Although也可以用though或者even though来代替。

千万不要跟but连接，but连接的是一个复合句，although引导的从句跟主句构成一个复杂句，两个都有的话就不伦不类了.

no matter+疑问句

这里的让步是”未知情况”,但依旧”不管如何…”
No matter what happens,I will not wat the carrot.
不管什么事情会发生，我都不会吃这胡萝卜.

No matter who orders me,I will not wat the carrot.
不管谁命令我，我都不会吃这胡萝卜.

No matter how hungry I am ,I will not wat the carrot.
不管我有多饿，我都不会吃这胡萝卜.

no matter 也可以用 regardless of来取代.
Regardless of what kind of video I make,you will give me a thumbs-up.
不管我做什么样的视频，你都会给我点赞.

6、方式状语从句

最常见的是两种”方式”

好像某事发生过的方式
好像某事正在发生的方式

I feel good as if I just ate a carrot
我感觉良好，就好像我刚吃了根胡萝卜一样.

You spend (so much) money as if you were a millionaire.

Eat the carrot as I do.
像我一样吃胡萝卜。

Leave the carrot as it is.
别动这胡萝卜.

7、原因状语从句

和目的结果状语从句都隐含了一种A->B的因果含义.

The rabbit ate the carrot because he was hungry.
兔子吃了胡萝卜，因为他饿了.

since

Since you are hungry,you cat eat the carrot.
既然你饿了，你可以吃这胡萝卜.

as

As you were not here,we ate the carrot without you.
因为你之前不在这儿，所以吃胡萝卜没带你一个.

because，since，as区别

1、从因果/语气上来说
because>since>as

because引出的是实实在在的因果关系.
Because this video is excellent,you should give it a thumbs-up.
因为这视频很棒，所以要点赞

since引出的是大家都已经知道的情况.
Since all my videos are excellent, you should give this video a thumbs-up.
众所周知，我的视频是精品，所以你要点个赞。

as引出的是显而易见的事实，比如：
As I have thick skin，I’m begging you for a thumbs-up.
显而易见我脸皮很厚，所以我求你点赞。

2、从语序上的区别
because引导的从句在主句前后都可以
而since和as引导的从句一般只能放在主句之前.

有时候我们会用for来表因果，但是for不能引导从句，所以构成的是一个复合句.for不可以替代because，因为含义都不同了。for通常表推测的原因。

Because you like me,you have given all my videos a thumbs-up.
因为你喜欢我，所以你个给所有英语兔的视频都点赞了.

you must really like me（推测的结果）,for you have given all my videos a thumbs-up（这么推测的原因）.
你一定很喜欢我，因为你给所有我的视频都点赞了.

8、目的状语从句

也有一定的因果关系，只不过使用”目的”的方式说出来的
从句 <= 主句
目的(“A”) <= 事件(“B”)
做事件B是为了达到目的A

In order that I could finish the video in time，I pulled an all-night.
为了即使完成视频，我熬夜不睡觉.

也可以改为

I pulled an all-night. so that I could finish the video in time.

so that 不能放在句首。

目的状语从句中，一般使用情态动词can,could,may,might,should,would等更好的体现目的性。

9、结果状语从句

结果状语从句也可以由so that 构成.
比如
The temperature was low so that the lake froze.
气温很低，所以湖结冰了.

气温很低的结果导致了湖结冰，这里并不是目的，而是结果.

我们也可以用so…that..的结构，但是不能单单用so，这就好比用but和for，只有so的话构成的是复合句而不是主句从句这种复杂句子.

I ate so many carrots for lunch that I felt sick afterwards.
我吃了那么多胡萝卜，导致(结果是)我之后感到不舒服.

除了so…that…，还有such …that…
It was such a tasty carrot that I ate it all at once.
这个是如此好吃的胡萝卜，以至于(结果)我一下子就吃完了它.

但是such后面只能接名词.so后面接形容词.

五、总结

1、从句的分类

名词性从句：主语从句、宾语从句、表语从句、同位语从句
定语从句(形容词从句)
状语从句(副词从句)

2、定语从句

关系词：that、who、whom、whose、which、where、why、when

3、主语从句

引导词：that、Whether、Where、When、How、Who、What

4、宾语从句

引导词：whether、who、what、where、when、how、that(往往可省略)

5、表语从句

类别	系动词
be动词	am,is,are
感官	look,sound,taste,smell,feel
状态	keep,stay,remain,stand,lie
变化	get,become,grow,turn,go,come,fall
显得	appear,seem
终止	prove,turn out

6、同位语从句

引导词：that、whether、who

7、宾语补语从句

冷门从句，引导词：who

8、时间状语从句

引导词：before、when、while、as、after、since、until、as soon as、the next time

9、地点状语从句

引导词：

where：哪里
wherever：不管哪里
everywhere：任何地方
anywhere：所有地方

10、比较状语从句

引导词：

比较级+than
as…as…
the(比较级),the(比较级)

11、条件状语从句

引导词：if、unless（除非）、provided、as long as、in case

12、让步状语从句

引导词：Event if、Although、though、even though、no matter+疑问句

13、方式状语从句

引导词：as if 、as

14、原因状语从句

引导词：because、since、as

15、目的状语从句

引导词：In order that、so that

16、结果状语从句

引导词：so that、so…that…、such …that…

参考：https://www.bilibili.com/video/BV1764y1f7nq?p=17&spm_id_from=pageDriver