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被动语态

助动词be + 及物动词的过去分词

含有情态动词：情态动词+ be + 及物动词的过去分辞

短语动词 ：example takes good care >> taken good care

虚拟语气

用来表示非真实的假设，表示命令、建议或说话人的主观愿望

条件从句 主句

违背现在事实 过去式 should / would / could / might + 动词原形

If the manager were here , he might make a decision immediately

违背过去事实 had + 过去分词 should / would / could / might + have + 过去分词

I could have done it better if I had been more careful

违背将来事实 should + 动词原形 should / would / could / might + 动词原形

were + 动词不定式( were to + 动词原形)

If it should rain tomorrow , what could we do ?

在下列结构的主语从句中，谓语动词用虚拟语气

It is necessary / imperative / important / essential / advisable that

It is proposed / desired / requested / suggested / recommended / demanded / decided / arranged that

混合虚拟句 条件从句表示的动作和主句表示的动作，在时间上不一致，动词形式需要调整

If you had taken the medicine yesterday , you would be well now。

Suggest , order , ask , demand , command , request , require etc.这些动词的宾语从句用虚拟句， 在这些动词后面的宾语从句中，助动词一律是should 。

It is ( It was ) important ，其后的主语从句用虚拟语气，助动词用should 。

It is important that we ( should ) learn computer .

Wish + ( that ) 从句，通常表示不可能实现的愿望。 表示现在的动作或状态是，从句中的动词用过去时；表示过去的动作或状态时，从句中的动词用had + 过去分词。

但是，从句中动词用would (might ) + 动词原形时，表示现在或将来有可能实现的愿望

I wish I knew a little contract law . 但愿我知道一点合同法（我不知道）

I wish you would come tomorrow . 我希望你明天能来 （有可能来）

As if / as thought 引导的状语从句（或表语从句）中，常用虚拟语气。

如果从句表示的意思与现在事实相反，谓语动词则应使用过去式；

如果从句表示的意思与过去事实相反，谓语动词则使用 had + 过去分词的形式 。