1.主语从句1）主语从句可直接位于主语的位置，如果从句较长，谓语又较短，可用it作形式主语，而将从句放在句末。
常见的句型有：*It is a fact\a pity\a question\good news that...*It seems\appears\happened\has turned out that...*It is clear\important\likely\possible that...*It is said\reported \has been proved that...It seems that the performance is very useful.2)what引导的主语从句表示“...的东西时”，一般不用it作形式主语。
*What we lack is experience.3)what,who,when,why,whether等词含有各自的疑问意义，但它们引导的主语从句，都用陈述语序。
*How the plan is to be carried out should be discussed again.*I did not know why I felt like crying.练习：1. It worried her a bit ____ her hair was turning grey.A. whileB. thatC. ifD. for2. ________ makes mistakes must correct them.A. WhatB. ThatC. WhoeverD. Whatever3. ________ Tom liked to eat was different from ________.A. That…that you had expectedB. What …that you had expectedC. That…what you had expectedD. What…what you had expected4. It ________ Bob drives badly.A. thinks thatB. is thought whatC. thought thatD. is thought that5. ____ we'll go camping tomorrow depends on the weather.A. IfB. WhetherC. ThatD. Where2.宾语从句1）宾语从句可位于及物动词、介词和某些形容词后。
连词that常可省略。
介词后一般接疑问词引导的宾语从句。
in that(因为),except that(除了),but that(只是）已构成固定搭配，其他介词后一般不接that引导的宾语从句。
*I promised that I would change the situation. （vt）*All this is different from what American young people would say about friendship. （prep）*He is certain that watching so much television is not good for children. （adj） *This article is well-written except that it is a bit too long. (介词的固定搭配）2)宾语从句后如有宾补，要用形式宾语it来代替，而把宾语从句移至宾补之后。
* He has made it clear that he would not change his mind.3)在think,believe,suppose,expect等动词后的宾语从句中，如果谓语是否定的，一般将否定词移至主句谓语上，宾语从句则变成肯定形式。
* He didn't think that the money was well spent.练习：1．—What did you parents think about your decision?—They always let me do ________ I think I should．A． when B． That C． how D． What2．Please remind me _________ he said he was going． I may be in time to see him off．A． where B． when C． how D． what3．Mary wrote an article on ________ the team had failed to win the game．A．Why B．what C．who D．That4．Someone is ringing the doorbell Go and see________．A ．who is he B． who he is C． who is it D． who it is3.表语从句表语从句出现在结构为“主语+系动词+表语从句”的句子中。
表语从句除可用that,what,when,why,whether,how等引导外，还可由because,as if(though)等引导。
that 常可省略。
如主句主语为reason,只能用that引导表语从句，不可用because.*Perhaps the most important thing to remember is that there is no one common type of life in America.*The reason why so many people died there is that there were not enough food supplies.* It looks as if successful international cultural communication will make the world smaller.练习：1 —I drove to Zhuhai for the air show last week .—Is that_____ you had a few days off？A. why B .what C. when D. where2 .I had neither a raincoat nor an umbrella ____I got wet through.A. It’s the reasonB. That’s whyC. There’s whyD. It’s how3. See the flags on top of the building? That was ______ we did this morning.A. whenB. whichC. whereD. what4. --- Are you still thinking about yesterday’s game?---Oh, that’s _____.A. what makes me feel excitedB. whatever I feel excited aboutC. how I feel about itD. when I feel excited4.同位语从句同位语从句用于对前面出现的名词作进一步说明，一般用连词that引导，由于先行名词的意义不同，也可用whether,who,when,where,what,why,how等引导。
常见的先行名词有 fact,idea,belief,news,hope,conclusion,suggestion,order,problem,report,decision. 有时由于谓语较短，将同位语从句位于谓语之后。
*She finally made the decision that she would join the fashion show.*I had no idea how many books I could borrow at a time.练习：1.The fact ____ he was successful proves his ability.A.thatB.whatC.whichD.why2.His suggestion ____ the meeting be delayed was turned down.A.whichB.thatC./D.it3.I have no idea ____ he will start.A.whenB.thatC.whatD./4.He often asked me the question ____ the work was worth doing.A.whetherB.whereC.thatD.when5.定语从句定语从句所修饰的先行词可以是名词或代词，也可以是一个句子。
定语从句通常位于先行词之后，由关系代词或关系副词引导。
*限制性定语从句限制性定语从句修饰先行词，对先行词起修饰作用，紧接先行词之后，无逗号，若省去，原句意思不完整。
引导定语从句的关系代词有who,whom,whose,which,that等。
who,whom,whose用于指人，whose有时也可指物，相当于of which；which用于指物；that 既可指人也可指物，但只用于限制性定语从句中。
关系代词除了引导定语从句，替代先行词外，还在从句中担任主语、宾语、定语等。
*Those who live alone or who are sick may have trouble in getting close to other people.*The girl whose parents died in an accident is living with her grandmother. 1) 当先行词是all,anything,everything,something,nothing等不定代词或先行词前有 first,last,any,few,much,some,no,only以及形容词最高级修饰时，只能用关系代词that 引导从句。
*That is all that I've heard from him.*He's the first person that I'm going to interview this afternoon.2) 关系代词的省略在从句中作宾语的关系代词常可省略。