虛擬語氣分三種情況來掌握：
1、虛擬條件句。
2、名詞性虛擬語氣。
3、虛擬語氣的其他用語。
一、虛擬條件句：
條件狀語從句是非真實情況，在這種情況下要用虛擬語氣。
1、條件從句與現(xiàn)在事實不一致，其句型為：
If 主語＋過去時，主語＋should（could， would， 或might）＋動詞原形，如：
If I were you， I would study hard.
If it rained， I would not be here now.
2、條件從句與過去事實不一致，句型為：
If 主語＋had＋過去分詞，主語＋should（could， would， 或might）＋have＋過去分詞，如：
If the doctor had come last night， the boy would have saved.
If I had not studied hard， I would have failed in the exam last term.
3、條件從句與將來事實不一致，句型為：
＋do，主語＋should（could…）＋ 原形 do
過去時（與現(xiàn)在事實條件句一樣）。
If it should rain tomorrow， we would stay at home.
If I were to go to the moon one day， I could see it with my own eyes.
If you missed the film to night， you would feel sorry