if引导的条件状语从句和虚拟语气的区别

if引导的条件状语从句所引导的是原因状语;可以是现实生活中已经出现的真实事件或有可能出现的事情;发生的可能性较大..而虚拟语气所引导的往往是非真实的;对于过去;现在或将来的虚拟或推断;发生的可能性较小;或已经不可能发生了 可以从2个角度去区分： 1..时态

A;由if引导的条件状语从句通常都是主句为一般将来时;从句为一般现在时..

B;而在虚拟语气中;时态都是有很多;往往都是根据句子的含义判断;究竟是与现在;过去还是将来的事实相反.. 2..真实与非真实

A;由if引导的条件状语从句一般都是真实的;只要所谓的条件成立;一定会成为事实

B;但虚拟语气并非如此;if; 既然是虚拟;就一定是非真实的;可以根据句意判断其是...

条件状语从句

连接词主要有 if; unless; as/so long as; on condition that 等..if 引导的条件句有真实条件句和非真实条件句两种..unless = if not. 例如：

Let's go out for a walk unless you are too tired. 如果不太累;我们去散散步..

If you are not too tied; let's go out for a walk. You will be late ___ you leave immediately. A. unless B. until C. if D. or

答案A..句意：除非你立即走;否则你就回迟到的..可转化为 If you don't leave immediately; you will be late..B、D句意不对;or表转折;句子如为 You leave immediately or you will be late. 虚拟语气

1虚拟语气用来表示说话人的主观愿望或假想;所说的是一个条件;不一定是事实;或与事实相反..虚拟语气在条件句中应用比较多..

2条件句可分为两类;一类为真实条件句;一类为非真实条件句..非真实条件句表示的是假设的或实际可能性不大的情况;故采用虚拟语气.. 真实条件句用于陈述语气;假设的情况有可能发生.. 一般现在时

shall/will + 动词原形 祈使句 情态动词一般现在时

例如：If he comes; he will bring his violin. 如果他来;会带小提琴来的..

The volleyball match will be put off if it ___. A. will rain B. rains C. rained D. is rained 答案B..真实条件句主句为将来时;从句用一般现在时..

注意：

1在真实条件句中;主句不能用be going to表示将来;该用shall; will. 错 If you leave now; you are never going to regret it. 对 If you leave now; you will never regret it. 2表示真理时;主句谓语动词不用shall will +动词原形;而直接用一般现在时的动词形式.. 非真实条件句

1虚拟语气可以表示过去;现在和将来的情况;时态的基本特点是时态往后推移..

a. 与现在事实相反的假设

一般过去时be用wereshouldwould等 +动词原形

例如：If they were here; they would help you. 如果他们在这儿;会帮助你的..

含义：They are not here; they can’t help you. b. 与过去事实相反的假设 过去完成时

shouldwould等+ have+ 过去分词 例如：If he had come yesterday; I should / would have told him about it.如果他昨天来的话;我会把这件事告诉他的..

含义：He did not come yesterday; so I did not tell him about it. c. 表示对将来不大可能发生的事情的假想 一般过去时

should/would等 + 动词原形 were+ 不定式 should+ 动词原形

例如：If you succeeded; everything would be all right. 如果你将来成功了;一切都会好的..

If you should succeed; everything would be all right. If you were to succeed; everything would be all right.

含义：You are not likely to succeed; everything will be what it is now.