if的主要用法总结讲义--高三英语一轮复习.docx

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1、If用法总结一、if引导状语从句，有“如果”之意。1.1 would appreciate it if you give me the chance.2.If we dont stop climate change,many animals and plants in the world will be gone.（主将从现）3.If I were you, I wouldnt go there.（虚拟语气）4.he had not hurt his leg,John would have won the game.（2007 全国）二、if引导名词性从句，有“是否”之意。Lit doesn*

2、t matter if you go to attend the meeting.（主语从句）2.1 wonder if you will consider my application. （宾语从句）3. At first he hated the new job but decided to give himself a few months to see it got any better.（2009北京）注：引导名词性从句的whether/if意为“是否”。在使用时，要注意两者存在以 下区别。1 .在主语从句中，whether既可引导位于句首的主语从句，也可引导用it作形式 主语的主语

3、从句，而if只能引导以it作形式主语的主语从句。如：Whether the work can be completed on time is doubtful.It is doubtful whether/if the work can be completed on time.2 .在宾语从句中，当其后紧跟ornot时，只能用whether,不能用if。如：I dont care whether/if he comes or not.I dont care whether or not he comes.3 .在介词后面的宾语从句中，只能用whether,不能用if。如：It all dep

4、ends on whether they will come back.4 .在表语从句和同位语从句中，只能用whether,不能用if。如：The problem is whether the money will be enough.I have no idea whether the money will be enough.三、what if 假使将会怎么样”之意。1 .What if it rains tomorrow?2 . What if that dream comes true?3 .What if this doesnt work out?4 .So what if he

5、was late. Who cares?四、only if 只当；只要；也许；只有；除非”之意。l.You can make progress only if you are modest.2.Only if you take an active part in physical activity will you be able to keep fit and stay healthy.3. Only if a teacher has given permission is a student allowed to enter the room.注：only if置于句首时，主句局部倒装。五

6、、if only ”只要；要是多好”之意。l.If only I werent so nervous.2.1f only I had done something then!3.If only grandfather would come!注：要使用虚拟语气。六、as if/though 好像,似乎”之意。l.He behaved as if nothing had happened.2.It seemed as if she been gone forever.3.1 can remember our wedding as if it were yesterday. 注：多用虚拟语气。七、e

7、ven if 即使；虽然”之意。1. Even if I had the talent to play tennis I couldnt stand the pressure.2. We wont give up even if we should fail 100 times.3. He is so busy.He can not afford enough time with his son even if he wants to.（2013 四川）八、if的省略结构Uf necessary, ring me at home.2.1f possible, let me know beforehand.3.There are few people nowadays, if any, who remember him.4.She seldom, if ever, goes to the cinema.5.He may be busy. If so, Til call later. If not, can I see him now?