1. 主语从句，句子是另一个句子的主语
 1)除谓语要管时态不能是句子外，主/宾/定/状/表都可以是句子。
 2)名词性从句，主/表/宾从句用法相当于名词，所以叫名词性从句
 3)包含从句的句子是主句，从句在主句中是什么成成份就叫什么从句
 4)从句的否定和疑问形式都在在主句上变，把主句的谓语变成否定和疑问即可
 5)关联词是从句的标志，一般以wh开头，放在从句前，用来引导从句，后面从句要用陈述语序
  常见关联词有who/when/where/why/whether/how/what等  例：What you need is just rest.
 6)还有特殊关联词that，它与wh关联词不同的时，wh开头的词不能省略，少了意思不完整，that少了意思也完整
  例：That the earth goes around the sun is true./What she wants is just money
 7)使用什么关联词主要看句子是否完整，句子完整就用that引导，不完整就根据需加以wh开头的关联词
  例：when she will come is not known./who kill rabbit Roger is still a mystery.
  例2：That English is an international language is a fact //这句头重脚轻
 8)当从句头重脚轻时，要借用形式主语it，以把句子啰嗦的放后面
  It's a fact that English is an international language. 英语是一种国际语言，这是一个事实
2. 表语从句，放在be动词后，常见关联词有how等，详见主语从句最后
 1)表从和主从用法一样，和主从在区别是所处位置不同，
 2)表从放be动词之后，且没有形式主语一说
  例：The problem is how we can see him. 问题是我怎样才能见到他
3. 宾语从句
 1)宾从是把从句放在动词和介词后作宾语的句子，和主从和表从差不多，都是由关联词引导且后加陈述语序
  例：You can get what you want //放动词后
   my father was satisfied with what I did //放介词后
   I could say nothing but that I was sorry.
 2)有时宾从可省略介词，如：I am sure (of) that.../I am afraid (of) that.../I am glad (of) that...
  例：I am sure that he will come/I am afraid that I have to go/I am glad that you have come
 3)宾从除of外还可省略that
  例：I am sure he will come/I am afraid I have to go/I am glad you have come
 4)宾从也有形式宾语it，借用它把啰嗦的宾语放后面
  例：I think it necessary that you remember it 我认为你很有必要记住它
   //第一个it是think的宾语，已有necessary修饰，就用it做形宾，把啰嗦的从句放后面
  例2：She makes it clear that she doesn't like swimming //make it clear明确表示
 5)直接引语与间接引语的宾从，直宾变间宾
  例：she said: "I will go home" //直接引用别人的话叫直引有引号
  例2：she said she will go home. //间引
 6)宾从同其它从句特别的是，宾从要随主句时态变化而变化，即上句中的间引应改为
  She said she would go home.
 7)直引变间引宾从，除人称，时态有要变化外，一些表时间的词也要变化
  例：He said:"I am twenty years old today!"——He said he was  twenty years old that day.他说那天他二十岁
  //I变he，时态变过去，今天天那天
4. 定语从句，定语是修饰名词的词，
 1)用句子来修饰名词就是定语从句，
  例：God helps those who help themselves. //who引导的定从，who help themselves表上帝帮助的对象
 2)定语从句修饰的词叫先行词，定语从句用什么关联词和它修饰的先词行有关，先行词是人，就用who引导
  例：God help those who help themselves. //先行词是人
 3)先行词是物就用that或which来引导
  I like the book that you gave me.  //that做gave的宾语可省略
  I like the book which is interesting. //which代替前面先行词做主语不能省
 4)读定从首先要找被定从修饰的先行词，一般关联词紧跟先行词后引导从句，所以找到关联词先行词就好找了
  例：There was a young man who liked adventure 有个喜欢冒险的年青人 //先行词man
   The house which/that stands on the hill is mine. //先行词house
 5)Thank you for the recorder/You gave me the recorder.
  ——Thank you for the recorder that/which you give me. 谢谢你给我的录音机
  That person who is talking with the teacher is my father. //先行词that person是人关联词用who
 6)限定性定从用于修饰和限定先行词，修饰的词表一个/些/类特定人或物，删去句子意思不清，且定语前没有标点符号
  例：This is the man who gave me this book. //删去定从This is the man意思不完整
 7)非限定性定从是先行词的附加修饰，是对先行词或主句的进一步说明，删去不影响基本意思，常加逗号把主从句分开
  例：LiMing, who is in the room, wants to ask you some questions. 在房间里的LiMing想问你一些事情
   //删掉who is in the room主句LiMing wants to ask you some questions意思仍完整
 8)还有以其它wh开头的关联词，如：when/where/whose等
5. 状语从句，学状从就是学状从的关联词
 1)表时间的关联词导时间状从 when/while/after/before 当..时候/在..同时/在..之后/在..之前
  例：When I was young, I'd listen to the radio, waiting for my favorite songs.
   When it rains, I usually go to work by bus.
 2)一般可用while可用代替when，但有时while还暗含强调对比的意思
  例：I was doing my homework while my brother was playing games.
   While I am working, Tom is playing computer game.
   While his wife was doing shopping upstairs, he just sat downstairs and waited for her. //while也可引导不含对比的
 3)after和before的用法
  例：I got up before then sun rose/Read the manual carefully before you operate the machine
   They went on working after the rain stopped.
 4)where引导地点状从 where 在..地方
  例：I'll go where the sky is blue./where there is a will, there is away. 我要去的地方是有蓝天的地方
 5)because引导原因状从 because
  例：Dont't take it for granted because it is not that simple.
   He didn't see the movie because he saw it./He didn't see the movie because he had seen it.
 6)if引导的条件状从 例：If you work hard, you will succeed.
 7)连接状语从句的关联词不仅是状从的标志，还决定了状从的类型，除此之外还有although/thought等引导的让步状从
  so that/in order that(为了)引导的目的状从
  例：Althought he is young, he knows a lot of things 虽然他很小，但是他知道的很多

4. 虚拟语气从句，常用以表与事实相反的假设或主观愿望
 1)用来相和事实相反的假设或主观愿望
  例：If I were you, I would not be bothered by English.
  //注：if表假设，分真实条件句与非真实条件句，上面是非真实，要用虚拟语气
   If it's sunny, I'll go to work by bike.