虚拟语气在条件句中的运用

　　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或实际可能性不大的情况，故采用虚拟语气。

　　例如：

　　If he doesn't hurry up,he will miss the bus.如果他不快点，他将错过巴士。( 真实)

　　If he is free,he will ask me to tell stories.如果他是空闲的，他会要求我讲故事。(真实)

　　If I were you,I would go at once.如果我是你，我马上就会去。(我不可能是你。非真实，虚拟语气，与事实相反)

　　If there were no air,people would die.如果没有空气，人就会死亡。(不可能没有空气。非真实，虚拟语气，与事实相反)

　　1、表示与事实相反的情况

　　从句：If+主语+过去时(Be动词用were)

　　主句：主语+ should/would/might/could+do：

　　1.If I were you,I would take an umbrella.

　　如果我是你，我会带把伞。(事实：我不可能是你)

　　2.If I knew his telephone number,I would tell you.

　　如果我知道他的电话号码，我就会告诉你。(事实：不知道)

　　3.If there were no air or water,there would be no living things on the earth.

　　如果没有水和空气，地球上就不会有生物。(事实：地球上既有空气也有水)

　　4.If I had any money with me,I could lend you some.

　　如果我带钱了，我就会借给你些。(事实：没有带钱)

　　5.If he studied harder,he might pass the exam.

　　如果他再努力些，就能通过考试了。(事实：没有努力)

　　6.If I were you, I'd wear a shirt and tie.

　　如果我是你，我就会穿衬衫和领带。(事实：我并不是你)

　　2、表示与过去事实相反的情况

　　从句：If+主语+had+done

　　主句：主语+should/would/might/could+have done

　　eg：

　　1. If I had got there earlier,I should/would have met her. 如果我早到那儿，我就会见到她。

　　(事实：去晚了)

　　2.If he had taken my advice,he would not have made such a mistake. 如果他听我的劝告的话，就不会犯这样的错误了。

　　(事实：没有听我的话)

　　3.She looked at me as if I had been a stranger.

　　她看我的样子好像我是一个陌生人。(事实：我并非陌生人)

　　3、表示对将来情况的主观推测

　　从句：①if+主语+were to do (if 表示未来的虚拟语气独有形式，其他如wish， even if等词都没有该形式来表示未来的虚拟语气)

　　②if+主语+should+do

　　③if+主语+过去式(be动词用were)

　　主句：主语+should/would/might/could+do

　　eg：

　　1.If he should come here tomorrow,I would talk to him.

　　如果他明天来这儿的话，我就跟他谈谈。(事实：来的可能性很小，不可能)

　　2.If there were a heavy snow next Sunday,we would go skating.

　　如果下周日下大雪，我们就去滑冰。(事实：下雪可能性很小，不可能)

　　3.If she were to be here next Monday,I would tell her about the matter.

　　如果她下周一来这儿的话，我就会告诉她这件事的始末。(事实：来的可能性很小，不可能)

　　4、 有时，虚拟条件句中，结果主句和条件从句的谓语动作若不是同时发生时，虚拟语气的形式应作相应的调整。这种条件句叫错综条件句。

　　①从句的动作与过去事实相反，而主句的动作与正在发生的事实不符。

　　eg：

　　If I had worked hard at school,I would be an engineer,too.

　　如果我在学校学习刻苦的话，我现在也会成为一个工程师了

　　If they had informed us,we would not come here now.

　　如果他们通知过我们的话，我们现在就不会来这里了。

　　②从句的动作与现在事实相反，而主句的动作与过去事实不符。

　　如：

　　If he were free today,we would have sent him to Beijing.

　　如果他今天有空的话，我们就已经派他去北京了。

　　If he knew her,he would have greeted her.

　　要是他认识她的话，他肯定会去问候她了。

　　5、 当虚拟条件句的谓语动词含有were,should,had时，if可以省略，这时条件从句要用倒装语序，即把were,should,had等词置于句首，这种多用于书面语。eg：

　　Should he agree to go there,we would send him there.

　　要是他答应去的话，我们就派他去了。

　　Were she here,she would agree with us.

　　如果她在这儿的话，她会同意我们的。

　　Had he learnt about computers,we would have hired him to work here.

　　如果他懂一些电脑知识的话，我们已经聘用他来这里工作了。

　　6、非真实条件句中的条件从句有时不表达出来，只暗含在副词、介词短语、上下文或其他方式表示出来，这种句子叫做含蓄条件句，在多数情况下，条件会暗含在短语中，如without…，but for…(要不是因为...)等

　　eg：

　　But for his help,we would be working now.

　　要不是他的帮助，我们还会在工作呢。

　　Without your instruction,I would not have made such great progress.

　　要是没有你的指导，我不会取得如此大的进步。

　　We didn't know his telephone number,otherwise we would have telephoned him.

　　我们不知道他的电话号码，否则我们就会给他打电话。

　　7、 有时，虚拟条件语气的从句中，主、从句可以省略其中的一个，来表示说话人的一种强烈的感情。

　　①省略从句

　　He would have finished it. 他本该完成了。

　　You could have passed this exam. 你本能通过这次考试的。

　　②省略主句

　　If I were at home now. 要是我现 在在家里该多好啊。

　　If only I had got it. 要是只有我得到它了该多好啊。

　　8.注意，在虚拟语气的从句中，动词be的过去时态一律用were，不用was。

　　eg：If I were you,I would go to look for him.

　　如果我是你，就会去找他。