虚拟语气的用法归纳如下：
名词从句中的虚拟语气
主语从句：表示建议、命令、要求、惊异和失望等。
形式：`（should） + 动词原形`。
条件从句中的虚拟语气
基本形态：
现在：`did / were`，`would （should, might, could） + do`
过去：`had done / had been`，`would （should/might/could） + have done （been）`
将来：`were to / should + do`，`would （should, might, could） + do`
与现在事实相反：`If I had enough money, I would buy a book.`
与过去事实相反：`If I had had enough money, I would have bought a book.`
与将来事实相反：`If I were to have enough money, I would buy a book.`
其它情形中的虚拟语气
wish：表示不能实现的愿望。
would rather：表达偏好。
it’s high time：表达应该做某事。
if only：表达强烈的愿望。
lest：表达防止某事发生。
错综、混合虚拟语气
当从句和主句的谓语动词时间不一致时，使用混合型虚拟语气。
状语从句中的虚拟语气
If引导的条件句：
表示与现在事实相反：`If + 主语 + 动词（过去式）， 主语 + would （should, might, could） + 动词原型`
表示与过去事实相反：`If + 主语 + had + 动词（过去分词）， 主语 + would （should, might, could） + have + 动词的过去分词`
表示与将来事实相反：`If + 主语 + were to + 动词原型， 主语 + would （should, might, could） + 动词原型 / 动词的过去式`
示例
与现在事实相反：`If I were you, I should study English.`
与过去事实相反：`If you had taken my advice, you wouldn’t have failed in the exam.`
与将来事实相反：`If it were to rain tomorrow, we would have to put off the visit to the Yangpu Bridge.`
以上是虚拟语气的基本用法归纳，请根据具体情况选择合适的虚拟语气形式