if条件句中的时态应用

if条件句中的时态应用if是高考考查热点之一。同学们往往把它的时态容易判断错误。笔者就if中的时态应用总结如下：一意“如果” 表真实条件。引导真实条件句。从句要求用一般现在时表将来。If it rains tomorrow , we ll stay at home.如果明天下雨的话，我们将呆在家里。If they come tomorrow , well have a meeting. 如果他们明天来的话，我们就开个会。注意：在表示“愿意”或“不愿意”时，if 后可以跟will 或wont.。如:If you wont go , Ill go alone.如果你愿意去，我就自己去。二意“假如” 表虚拟条件。引导虚拟条件句。表示与事实相反的假设。虚拟条件句和主句的时态构成如下：虚拟情况从句时态主句时态与现在事实相反一般过去时(be 用were)would (should ,could ,might)+动词原形与将来事实相反一般过去时(be 用were)should +动词原形were to +动词原形would (should ,could ,might)+动词动词原形与过去事实相反过去完成时would (should ,could ,might)+have+过去分词If I were a bird ,I could fly in the air .如果我是一只小鸟，我就会在天上飞。If I had enough money now, I would lend it to you .如果我现在有足够钱的话，我就会借给你。If it should rain tomorrow, the race would be put off.如果明天下雨的话，比赛就会推迟。If you had arrived earlier that day , you might have met her.如果那天你早点到的话，你就会遇见她了。三意“是否，是不是”引导间接问句。当主句为现在时时，从句应用适当的时态。当主句为过去时时，从句应当遵循时态一致的原则，要采用相应的过去时态。I dont know if they will come tomorrow.我不知道他们明天是否会来。He asked if they would come the next day.他问他们第二天是否会来。注意：在正式的文件中，若句中有助动词had 、were 、should，则将其提前，省略if.Had it not been for your help,we would not have achieved so much.要不是你的帮助，我们不会取得如此大的成绩。 四固定搭配： if only :意“要是就好了”，表示一种不真实的条件。其后接从句。从句用虚拟语气。用一般过去时表示现在没有实现的愿望；对过去没有实现的愿望从句用过去完成时。If only I had taken mothers advice.我要是听妈妈的建议就好了。If only I could speak several foreign languages .我要是能讲几种外语就好了。区别 only if: :意“只有在条件下才”用来加强从句的语气。当其位于句首时，主句用倒装语序。He would succeed only if he tried hard .Only if he tried hard ,would he succeed.只有他努力他才会成功。:as if /though意“好象”引导状语从句或表语从句。当从句的内容为不真实情况时要采用虚拟语气。与现在事实相反从句用一般过去时，与过去事实相反从句用过去完成时。与将来事实相反从句用would (could ,might )+动词原形She cried as if her heart could be broken.她哭得好象心都要碎了。:even if 意“即使、纵使”连词，引导让步状语从句。Even if he is poor ,she loves him.即使他很穷，她仍然爱他。 【巩固练习】1She seldom ,_,blames her failure on others.A. if ever B. if any C. if necessary D. if possible2. I had never spent a more worrying day. It seemed _the day would never end.A. as if B. even if C. as soon as D. as long as 3. If a man _succeed, he must work as hard as he can .A. will B. is to C. is going to D. should 4. If it _tomorrow, well go roller-skating.A. isnt rain B. wont rain C. doesnt rain D. doesnt fine5.I think it is necessary for my 19-year-old son to have his own mobile phone,for I sometimes want to make sure if he _ home for dinner .(06高考)A .come B .comes C. has come D . will come6 .In time of serious accidents ,_we know some basic things about first aid ,we can save lives.（06高考）A . whether B. until C .if D .unless7 .If you _ wait over there for a minute ,Mr. Smith ,Ill tell our manager youve arrived.A. must B. should C. will D. can8._ for the doctors careful treatment ,he _till last year.A. If it is not ;cant liveB. Were it not ;couldnt liveC. Had it not been ;couldnt have lived D. If it wasnt ;cant live9. It would be impossible for him to leave hospital tomorrow if he _first aid when the accident happened.A hadnt be given B .wasnt be given C. shouldnt be given D. wouldnt be given10.If I _plan to do anyth