he opened his lips as if he were to speak. as if 后接对过去的虚拟不是应该用had done吗 为什么用were

as if后面接的未必都要用虚拟语气，楼主的这道句子就不是，只是陈述一个相近的事实。
关于as if 的用法，请注意以下几个问题：
1. as if 引导的从句经常用虚拟语气。如果从句表示的动作发生在过去，用过去完成时；指现在状况，则用一般过去时；指将来状况则用过去将来时。
说明as if 从句表示的意思与事实不符或者相反。例如：
He walks as if he were drunk.
My neighbor treats the child as if he were their own son.
2. 但是，如果句子表达的意思与事实并没有什么不符，那么就不使用虚拟语气。例如：
He heard a noise, as if someone was breathing.
It looks as if it is going to rain.
3. as if 经常和look, seem 连用。例如：
She looks as if she is (were) ill, because her face is pale.
It seemed as if there was a fight between the two sides.
4. as if 从句中的主语如果和主句主语相同，而且谓语动词有be, 则从句主语和谓语经常省略。例如：
She stood at the gate as if (she was) waiting for someone.
The teacher shouted at the boy as if (he was) angry.
望对你有所帮助(*^__^*) ~

这里不是虚拟语气。as if或as though后，不见得都用虚拟语气。
当表示有可能发生的事情时，用陈述语气：
It is getting darker and darker, as if it is going to rain.
当从句起修饰作用时，我们能确定不是真的事实时，用虚拟语气。
The woman police looks after the lost child very,very well,as though she were his mother.

这里不是虚拟语句，这是过去式。

这不是虚拟语气，只是表示说 好像的意思吧……
不是英语专业 勿喷~~