來歷是有三個時態的虛擬語氣,都有用到should
（if引導的）從句中的v.主句中的v.
現在 did / were should / would / might / could + do
過去 had done / been should / would / might / could + have done / been
將來 were to / should + do should / would / might / could + do
給你造幾個句子,看看能不能更清楚：
現在 If I were a train,I should travel to all the splendid scenes in this planet.
過去 If you had not been a queer,you should never have broken your mom"s heart.
將來 If our team were to undermine the opponent"s reputation for our own good,we should be sorry.
來歷是有三個時態的虛擬語氣,都有用到should
（if引導的）從句中的v.主句中的v.
現在 did / were should / would / might / could + do
過去 had done / been should / would / might / could + have done / been
將來 were to / should + do should / would / might / could + do
給你造幾個句子,看看能不能更清楚：
現在 If I were a train,I should travel to all the splendid scenes in this planet.
過去 If you had not been a queer,you should never have broken your mom"s heart.
將來 If our team were to undermine the opponent"s reputation for our own good,we should be sorry.