虛擬語氣分為：與現(xiàn)在事實相反,與過去事實相反,與將來事實相反
第一種：與現(xiàn)在事實相反,從句用過去時,did或were,主句用would+動詞原形
例句:If I were you,I would not study English.
第二種：與過去事實相反,從句用had done,主句是would/could/should have done
例句：If you had come yesterday,you would/should/could have seen her
第三種：與將來事實相反,從句分三種
1、與現(xiàn)在事實相反用法一樣
2、were to do
3、should do這里should不可替換,主句用could/would +動詞原形
例句
1.If you came tomorrow,you would see me
2.If you were to come tomorrow,you could/would see me
3.If you should come tomorrow ,you could/would see me