一个英语语法，不能理解，大家帮一下！

在新概念里第24课里最后有一句话是这样的："Oh,that."he said with a smile as if he were talking about an old friend! .....这个句子里面的were为什么不是was?

虚拟语气,前面的人称无论是什么,都要用were

之所以用were而不用was是因为这是一个as if 引导的虚礼条件句，谓语动词都应该是“were”。

是虚拟语气的固定用法，这句话还不是很典型，非真实条件句 分三类

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

条件从句	主句
一般过去时（be用were）	should（would）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

条件从句	主句
过去完成时	should（would）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

条件从句	主句
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 no

这是虚拟语气，be 动词的过去式都要用 were.

as if是好像，这是虚拟语气，一般用were，比如“如果我是你的话”"if I were you"