虚拟语气

    1 ）概念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。

    2 ）在条件句中的应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的或实际可能性不大的情况，故采用虚拟
语气。

    1.1 真实条件句真实条件句用于陈述语气，假设的情况可能发生，其中 if
是如果的意思。

    时态关系句型：条件从句　　　主句一般现在时　　 shall/will + 动词原
形If he comes ， he will bring his violin.典型例题

    1.2 表示对将来的假想句型：　条件从句　　　　　　主句一般过去时should+
动词原形were+ 不定式　　　　 would +动词原形should+ 动词原形If you succeeded，
everything would be all right. If you should succeed，everything would
be all right. If you were to succeed， everything would be all right.

    1.3 混合条件句主句与从句的动作发生在不同的时间，这时主，从句谓语动
词的虚拟语气形式因时间不同而不同，这叫做混合条件句。

    If you had asked him yesterday， you would know what to do now.
（从句与过去事实相反，主句与现在事实相反。）

    If it had rained last night （过去）， it would be very cold today
（现在）。

    1.4 虚拟条件句的倒装虚拟条件句的从句部分如果含有were， should ，或
had ，可将if省略，再把were， should 或had 移到从句句首，实行倒装。

    Were they here now， they could help us. =If they were here now ，
they could help us. Had you come earlier， you would have met him =If
you had come earlier， you would have met him. Should it rain ， the crops
would be saved. =Were it to rain， the crops would be saved.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 ，即在从句中
be用were代替。

    If I were you ， I would go to look for him.如果我是你，就会去找他。

    If he were here ， everything would be all right. 如果他在这儿，一
切都会好的。

    典型例题_____ to do the work， I should do it some other day. A. If
were I　　 B. I were　C. Were I 　D. Was I答案C.在虚拟条件状语中如果有
were， should ， had这三个词，通常将if省略，主语提前，变成 were ， should，
had + 主语的形式。但要注意，在虚拟条件状语从句中，省略连词的倒装形式的
句首不能用动词的缩略形式。如我们可说 Were I not to do.，而不能说 Weren
‘t I to do.

    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
语动词便不用shall （will） +动词原形，而直接用一般现在时的动词形式。

    2.1 非真实条件句1 ）时态：可以表示过去，现在和将来的情况。它的基本
特点是时态退后。

    a.　同现在事实相反的假设。

    句型：条件从句　　　　　主句一般过去时　　　should（ would） +动词
原形If they were here ， they would help you. b.　表示于过去事实相反的
假设。

    句型：条件从句　　　　　主句过去完成时　　　 should （would ） have+
过去分词If she had worked harder， she would have succeeded. The rice
would not have been burnt if you had been more careful. If my lawyer had
been here last Saturday ， he would have prevented me from going. If he
had come yesterday， I should / would have told him about it. 含义：He
did not come yesterday， so I did not tell him about it. If he had not
been ill and missed many classes， he would have made greater progress.
含义： He was ill and missed many lessons ， so he did not make greater
progress.