對現在的虛擬：If 從句用一般過去時（be動詞一般只用were),主句用主語+would +動詞原形If I were a bird, I"d fly in the sky.If I had a million dollars, I"d travel around the world with my family.
1.與現在事實相反 If引導的從句動詞用過去式（be的過去式一般用were） 主句用主語+would / should / could / might + 動詞原形 eg: If I won the lottery, I would buy an expensive car. If I were you, I would give AIDS patient a hug.
2.與過去事實相反 If引導的從句用：主語+had +過去分詞 主句用主語+would / should / could / might have+過去分詞 eg: If he had driven more carefully, he would not have had the car accident yesterday.
3.與將來事實可能相反 If引導的從句動詞過去式 / should +動詞原形 / were to＋動詞原形 主句用主語+would / should / could / might +動詞原形 If it rained tomorrow, they wouldn’t go for an outing.
對現在的虛擬：If 從句用一般過去時（be動詞一般只用were),主句用主語+would +動詞原形If I were a bird, I"d fly in the sky.If I had a million dollars, I"d travel around the world with my family.
1.與現在事實相反 If引導的從句動詞用過去式（be的過去式一般用were） 主句用主語+would / should / could / might + 動詞原形 eg: If I won the lottery, I would buy an expensive car. If I were you, I would give AIDS patient a hug.
2.與過去事實相反 If引導的從句用：主語+had +過去分詞 主句用主語+would / should / could / might have+過去分詞 eg: If he had driven more carefully, he would not have had the car accident yesterday.
3.與將來事實可能相反 If引導的從句動詞過去式 / should +動詞原形 / were to＋動詞原形 主句用主語+would / should / could / might +動詞原形 If it rained tomorrow, they wouldn’t go for an outing.