☆各种虚拟句 ☆表示轻微责备or遗憾 情态v.(no)+ have done “本应(而实际却没…)” “本不该/必.(而实际却.)” was/were to have(been do one “过去计划中要做某事,实际上没 做
☆各种虚拟句 ☆表示轻微责备or遗憾 情态v. (not) + have done “本应…（而实际却没…）” “本不该/必…（而实际却…）” was/were to + have (been) done “过去计划中要做某事，实际上没 做
区别 shou|dn?t+ have done” 表示过去本不该做的事情 实际上却做了 “ needn't+ have done” 表示过去本不必做的事情 实际上却做了
区别: “shouldn’t + have done” 表示过去本不该做的事情 实际上却做了 “needn’t + have done” 表示过去本不必做的事情 实际上却做了
They shouldnt have left so early TYou neednt have bought it You neednt have come here yesterday
▪They shouldn’t have left so early. ▪You needn’t have bought it. ▪You needn’t have come here yesterday
principal forms of verbs third-person singular form past form past participle(pp present participle
principal forms of verbs third-person singular form past form past participle (p.p.) present participle
features x tense x voice x mood
features ＊ tense ＊ voice ＊ mood