if引导的从句有哪些if引导的假如条件句句子

if当假设引导条件状语从句。

if的用法：表示条件，意思是假设；表示虚拟，意思是假设；表示是不是的含义，和whether一样用法，连接宾语从句。 扩展资料

　　1.(表示条件)假设 ,主句用以后时,if从句用目前时表示以后

　　He will come if you invite him.

　　假设你请他,他会来的.

　　2.(表示虚拟)假设,要是

　　时态：可以表示过去,目前和以后的情况.它的`基本特点是时态退后.

　　a.同目前事实相反的假设.

　　句型 ：条件从句主句

　　大多数情况下过去时 should( would) +动词原形

　　If they were here,they would help you.

　　b.表示于过去事实相反的假设.

　　句型：条件从句主句

　　过去完成时 should(would) have+ 过去分词

　　If she had worked harder,she would have succeeded.

　　The rice would not have been burnt if you had been more careful.

　　If my lawyer had been here last Saturday,he would have prevented me from going.

　　If he had come yesterday,I should / would have told him about it.

　　含义：He did not come yesterday,so I did not tell him about it.

　　If he had not been ill and missed many classes,he would have made greater progress.

　　含义：He was ill and missed many lessons,so he did not make greater progress.

　　c.表示对以后的假想

　　句型：条件从句主句

　　大多数情况下过去时 should+ 动词原形

　　were+ 不定式 would + 动词原形

　　should+ 动词原形

　　If you succeeded,everything would be all right.

　　If you should succeed,everything would be all right.

　　If you were to succeed,everything would be all right.

　　3.是不是 = whether 连接宾语从句

　　I wonder if she is ill.

　　不了解她是不是病了.

1、I could do it now, if you like.

假设你愿意，我目前完全就能够做这事。

2、You can come with us if you want to.

假设你愿意可以跟我们一起来。

3、Put your hand up if you need more paper.

若有人还需要纸，请举手。

4、Only time will tell if the treatment has been successful.

唯有时间才可以证明这样的疗法是不是成功。

5、He must be 70 if hes a day!

他至少70岁了！

if 引导的条件状语从句有真实条件句和非真实条件句两种:

1、真实条件句：叙述真实可能出现的事情

例句：If you fail in the exam,you will let him down.

假设你考试不及格，你会让他失望的。

2、非真实条件句：虚拟语气的一种，表示与实质上已出现事实相反：

例句：If I were you, I would invite him.

假设我是你，我会邀请他。