浅谈英语三大从句
学习一门语言，就需要掌握它的语音，语法和词汇。
在英语中，长难句是重点，也是难点。长难句中通常有多余两个动词。如果一个句子中出现两个或两个以上的动词，这些动词之间一定要体现出关系。
这其中有一个主要动词，另外的动词可能是以非谓语的形式（现在分词表示伴随或者过去分词表示过去或完成）出现，也可能出现在从句中做谓语。
今天，我们来看一下英语的三大从句：名词性从句，形容词性从句（定语从句），以及副词性从句（状语从句）。
一、名词性从句 Nominal Clause：从句的作用是代替一个名词成分，比如主语，宾语，表语或者同位语。
常见引导词why, that, who, whether, how
That everyone knows him (主语从句) is unbelievable.
每个人都认识他(这件事)不可思议。
Why these animals disappeared(主语从句) is still a mystery.
Whether it is going to rain (主语从句) is unknown.
Who wrote this letter (主语从句) is a secret.
It is said that the population of India would exceed China(主语从句).
据说印度的人口将超越中国。此句中it是形式主语，新闻中常见。
I don"t know how I can drive to your place. (宾语从句)
I know that she is famous (宾语从句).
It is still a mystery why these animals disappeared(同位语从句).
The problem was that we couldn"t afford the fare (表语从句).
二、形容词性从句（定语从句）Attributive Clause
定语从句作定语，修饰主句的某个名词性成分，可以转换成汉语中的限定语来理解，又称为形容词性从句，相当于形容词，一般紧跟在它所修饰的词（英语称先行词）后面。
常见引导词 where, when, who, which, that, through
They have a meeting room where they welcome guests(从句).
这句话英语逐字释义是：他们有一个会议室，在那里他们欢迎客人。中文的表达习惯是：他们有一个(可以)欢迎客人的会议室。
而以下两个句子内容涵盖一样，但因为从句和主句的动词不同，表达的重点也不同。
Her brother who is twenty(从句) serves in the army.
Her brother who serves in the army (从句) is twenty years old.
第一句是：她的二十岁的哥哥在部队服役；第二句是：她的在部队服役的哥哥今年二十岁了。
The student who/which is select/picked is very smart.
The dress which is pickedis very beautiful.
There are many things that we can do to protect environment..
These books are for the children, some of which are difficult.
We bought a telescope through which we can see stars.
三、副词性从句（状语从句），起副词作用的句子，用作状语，基可以修饰谓语，定语和状语，也可以修饰整个句子。分为时间、地点、原因、条件、目的、结果、让步等从句。状语从句区别于定语从句的明显特征是状语从句没有先行词。
时间状语从句
After I had dinner last night, I went for a walk.
As soon as l arrived home, it started to rain.
地点状语从句
Please tell me where you come from. (如果是Please tell me the place where you come from则是定语从句)
原因状语从句
She needs some help because/as/since she is new here.
目的状语从句
I finished my work quickly so that/in order that l can attend his birthday party.
结果状语从句
They areso tired that they can"t continue.
让步状语从句
Even if/though they all speak English, they couldn"t understand each other.
条件状语从句
If you practice every day, you will improve your English.
l will not go there unless I"m paid.