一．用“及物动词+不定式”结构可以将含有that引导的某些宾语从句的复合句转换成简单句.例如：
1.He decided that he would buy a digital camera online.
→He decided to buy a digital camera online.
2.We hoped that we would come back soon.
→We hoped to come back soon.
3.I expect that I shall finish my work by this Sunday.
→I expect to finish my work by this Sunday.
二．用“疑问词+不定式“结构可以将某些含有连接代词或连接副词引导的宾语从句转换简单句.例如：
1.I don’t know which one I can buy .
→I don’t know which one to buy.
2.We wonder where we’ll go this Sunday.
→We wonder where to go this Sunday.
3.Could you please teach me how I can search the Internet?
→Could you please teach me how to search the Internet?
三．用“too…to…”结构可以将含有so…that引导的结果语从句(否定)的复合句转成简单句.如：
1.The boy is so young that he can’t look after himself.
→The boy is too young to look after himself.
2.The question is so difficult that I can’t answer it .
→The question is too difficult for me to answer.
四．用“…enough +不定式”结构可以将含有so …that …引导的结果状语从句（肯定）的复合句转变为简单句.例如：
1.The girl is so tall that she can reach the apples on the tree.
→The girl is tall enough to reach the apples on the tree.
2.This hall is so large that it can hold 2000 people.
→This hall is large enough to hold 2000 people.
3.The table was so light that the little boy can carry it.
→The table was light enough for the little boy to carry.
五．用“happen + 不定式”或“seem +不定式”结构可以分别将“It happens that…”和“It seems that… ”等含有主语从句的复合句转换为简单句.例如：
1.It happened that the teacher saw him playing in class.
→The teacher happened to see him playing in class.
2.It seemed that sharks have been on the earth for thousands of years .
→Sharks seemed to have been on the earth for thousands of years.
3.It seemed that this camera offered the most at the best price.
→This camera seemed to offer the most at the best price.
六．用“in order +不定式”或“so as +不定式”结构可以将含有so that 引导的目的状语从句的复合句转换为简单句.如：
1.She decided to buy a camera online so that she could receive it soon.
→She decided to buy a camera online in order to receive it soon.
→She decided to buy a camera online so as to receive it soon.
2.I went over my composition again and again so that I couldn’t make any mistakes.
→I went over my composition again and again in order not to make any mistakes.
→I went over my composition again and again so as not to make any mistakes.
3.Miyoko bought a camera so that she could take pictures in Beijing.
→Miyoko bought a camera in order to take pictures in Beijing.
→Miyoko bought a camera so as to take pictures in Beijing.
七．在某些作表语的形容词后面加不定式可以将某些含有状语从句的复合句转变成简单句.例如：
1.I was glad when I heard the good news .
→I was glad to hear the good news.
2.Tom’s parents were very surprised as they knew all about it.
→Tom’s parents were very surprised to know all about it.
多了点,不放便贴出来,你可以自己去看看,里面资料还是挺全滴～!
上面的是简单句改复合句,下面这个是复合句改简单句～!
不过最重要的还是要多练,多写几道题你就熟悉了!
希望能帮到你吧!*^-^*
希望对你能有所帮助.