If条件句.pptVIP

* if 引导的条件句 if引导的条件句表示在某种条件下，会导致另 一事发生。句式为if从句+ 主句。 中文意思是“如果某事发生（或不发生）， 另一事就（不）发生”。通常分以下两种情形： 一、真实条件句 二、虚拟条件句 一、真实条件句 if从句用一般现在时，主句用一般将来时，表示从句中 的动作如果发生，那么主句中的动作也将发生。如： If it stops raining later this afternoon, we will eat out. 2. if从句和主句都用一般现在时，表示客观真理或习惯 和持续发生的事情。如： If the moon goes near the earth, the tide goes high. 3. if从句用一般现在时，主句用祈使句，表示给某人提 建议或命令某人做某事，及提出建议或请求。如： If you are not likely to be in town, please let me know. 二、虚拟条件句 虚拟条件句，也称非真实条件句，表示在某种假想的 条件下，将导致某事发生。从句中所陈述的事情仅仅只是 说话者的想法，不是事实，也不可能发生。 虚拟语气是一种特殊的动词形式，表示所说的话不是 一个事实，而只是一种假设，愿望，建议，怀疑， 猜测或不大可能实现的空想。 If I have time, I will go with them. (陈述语气) If I were you, I would go with them. (虚拟语气) I.虚拟语气用在条件状语从句中 虚拟语气用在条件状语从句中，通常从句由连词if 引导。 1.与现在事实相反的虚拟条件句 ? 例 If I feared death, I wouldn’t be a Party member. 怕死就不做共产党员。 If there were no air, we couldn’t live. 如果没有空气，我们就不能生活。 主语+ would, should, could, might+动词原形 If +主语 +动词过去式(be的过去式用were) 主句 条件状语从句 1.I would ask George to lend us the money if I ______ him. A. had known?? B. knew?? C. have known?? D. know 2.I _____ it to him if I thought he would understand. shall explain? B. will explain? C. would explain? D. explain 2.与将来事实相反的虚拟条件句 构成 ? If he were to come tomorrow, things would be easier. 假如他明天会来，事情就容易办了。 主语+would, should, could, might+动词原形 If + 主语+ were to/ should +动词原形 If +主语 +动词过去式(be的过去式用were) 主句 条件状语从句 If the sea ____ to rise 50 feet, India would become an island. A. will??? B. is???? C. was???? D. were If you ____ see Mary, what would you tell her? A. are???? B. will be going?? C. must?? D. should 3.与过去事实相反的虚拟条件句 构成 例如 If there had been no air in the tube, the result would have been better. 主语+ would, should, could, might+ have + 过去分词 If + 主语 + 动词过去完成式 主句 条件状语从句 If you hadn’t gone with Tom to the party last night, _______. A. you would meet John already???? B. you won’t have missed John C. you will have met John????????? D. you would have met John 4.省略连词if 在条件状语从句中，如果有were, should, ha