if  conj 如果；是否

【讲解】：

1)if表“如果”,作状语从句连接词,(是有可能实现的事情)

例: Please let me know if he comes back.如果他回来,请让我知道

例: I will go if tomorrow is fine. 如果明天天好,我就去

注意:if引导的状语从句常用主将从现,这一特殊的时态

2) if表“如果”,作虚拟语气连接词,(是不可能实现的事情)

学习方法:区分有无可能实现,记清现在,过去,将来三种时间结构(详见语法虚拟语气)

要求:重点掌握现在时的虚拟语气结构,后两种优等生可适当关注.

例: I would work hard if I were you..如果我是你,我会努力学习的(我不可能是你,不可能实现.现在时的结构: 主+would +v原 ….if  主+did/were)

例: He would study German if he had time.如果他有时间,他将学习德语

例: I would have checked my paper again if I had had more time at yesterday’s examination.如果我在昨天考试时有更多时间,我会再检查一遍的(没有更多的时间,不可能实现)

过去时的结构: 主+would +have +过去分词 ….if  主+had+过去分词

例: If he had taken my advice, he would have succeeded in the competition.如果他听从了我的建议，他在比赛中应该已经获胜了。

将来时的结构: 主+would +v原 ….if  主+did/were)

注意:分清主将从现;和现在时的结构一致,但是从句后常用表将来的时间词

3)even if =though=although即使,连接让步状语从句

例: He improves himself in English little even if he studies hard.即使他学习很努力,英语仍少见提高

4) as if 虚拟语气连接词.好象,活似

例: The old man runs very fast as if he were a young man.这个老人跑得很快好像是个年轻人一样(as if引导的特殊虚拟语气. 主句正常时态 as if+ 主+过去时/were)

5)表“是否”=whether,作宾语从句连接词

即: if 有 “如果,是否”两个意思,whether只有 “是否”一个意思.

例: I didn’t know if/whether he will arrive tomorrow.我不知道他是否明天到。

注意: sure后只能用that,-- I am sure that…. 不用if/whether.

1）You will do much better __ you are more careful with your spelling.

A if     B before    C although   D unless 

答案：a

讲解：主将从现，翻译：如果你在拼写上更细心，你会做的更好。

2）–Come and join us, Jimmy!

-- I am sorry, but I am really busy now. If I __ time, I would certainly go.

A. will have     B. have had     C. had   D. have  

答案：c

讲解：如果我现在有时间,我一定去，表明我现在没有时间,和现在相反,现在时的虚拟语气，翻译：如果我现在有时间,我一定去。

3）_______I fail this time, I would try again.

A. Even if     B. As if     C. If 

答案：a

讲解：even if虽然，as if好像，翻译：即使我这次失败了，我还要再试试。

4）She ran _______the ghost were after her.

A. even if     B. as if     C. even though 

答案：b

讲解：even if虽然，as if好像，翻译：她跑得飞快好像魔鬼在追她似的。

5) Do you know ________ he's married?

A. even if     B. as if     C. if 

答案：c

讲解：even if虽然，as if好像，if是否，翻译：他结婚没结婚，你知道吗？