1.主語從句
1）主語從句可直接位于主語的位置，如果從句較長，謂語又較短，可用it作形式主語，而將從句放在句末。常見的句型有：
*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\estimated\has been proved that...
如：
It is said that comic books create a connection between people of the same generation.
It seems that the performance is very useful.

2)what引導的主語從句表示“...的東西時”，一般不用it作形式主語。
What we lack is experience.

3)what,who,when,why,whether等詞含有各自的疑問意義，但它們引導的主語從句，都用陳述語序。
How the plan is to be carried out should be discussed again.
I did know why I felt like crying.

2.賓語從句
1）賓語從句可位于及物動詞、介詞和某些形容詞后。連詞that常可省略。介詞后一般接疑問詞引導的賓語從句。in that(因為),except that(除了),but that(只是）已構成固定搭配，其他介詞后一般不接that引導的賓語從句。如：
I promised that I would change the situation.
All this is different from what American young people would say about friendship.
He is certain that watching so much television is not good for children.
This article is well-written except that it is a bit too long.

2)賓語從句后如有賓補，要用形式賓語it來代替，而把賓語從句移至賓補之后。
He has made it clear that he would not change his mind.

3)在think,believe,suppose,expect等動詞后的賓語從句中，如果謂語是否定的，一般將否定詞移至主句謂語上，賓語從句則變成肯定形式。
He didn't think that the money was well spent.

3.表語從句
表語從句出現在結構為“主語+系動詞+表語從句”的句子中。表語從句除可用that,what,when,why,whether,how等引導外，還可由because,as if(though)等引導。that常可省略。如主句主語為reason，只能用that引導表語從句，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.

4.同位語從句
同位語從句用于對前面出現的名詞作進一步說明，一般用連詞that引導，由于先行名詞的意義不同，也可用whether,who,when,where,what,why,how等引導。常見的先行名詞有fact,idea,belief,news,hope,conclusion,evidence,suggestion,order,problem,report,decision.有時由于謂語較短，將同位語從句位于謂語之后。如：
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.
The news came that their team had won the championship.