Could have…Would have…Should have…

Could have…Would have…Should have…

這些過去式情態助動詞都是用在假設的情況下，描述並沒有發生的事。

Could have+過去分詞 形容在過去有可能發生或你有能力辦到，但卻沒有發生的事情

例：

I could have married someone else but I chose you.

我可以嫁給別人但是我選了你。

We could have won the game if we’d trained more.

我們要是有多訓練的話就能贏得比賽了。

I could have written to him but I chose to call him instead.

我是可以寫信給他，但我選擇打電話給他。

He could have bought a jacket but he borrowed one from his friend.

他可以買一件夾克，但是他後來還是跟朋友借。

Couldn’t have+過去分詞 形容在過去不論什麼條件都不可能發生的事情

I couldn’t have arrived any earlier. There was a terrible traffic jam.

我不可能更早到，路上塞車很嚴重

He couldn’t have passed the exam, even if he had studied harder. It’s a really, really, really difficult exam.

他不可能考的過，即使他更努力準備，這次的考是真的，直的，真的很難。

Would have+過去分詞 用來形容在過去沒有發生的事情，但是比較常跟if一起出現，語氣也較肯定。

1.       是third conditional (與過去事實相反)的一部分。

  Third conditional = if +過去完成式，…would have +過去分詞

例：

If she’d had enough money, she would have bought both bicycles.

她如果錢夠的話，她會兩台腳踏車都買。

If I’d answered one more question right, I would have passed the test.

我如果多對一題的話，我就能通過考試了。

He could have made the team if he had trained harder.

他如果有更努力訓練，他就能考上校隊了。

2.      因為 would或will可以用來表示如果想要或不想要做某件事，我們可以用would have+過去分詞 我們想要做某件事但卻沒做。這跟third conditional很接近，但沒有用 “if”。

I would have gone to the party, but I was really busy.

我想去參加派對，但我太忙了。

I would have called you, but I didn’t know your number.

我想打電話給你，但我沒有你的號碼。

Should have+過去分詞

1.    Should have +過去分詞 指某件事其實是不錯的，但仍然沒做。常用在建議已發生的事，或後悔沒有做的事。

例：

You should have come to my birthday party last night, everyone missed you. 

昨晚你應該來我的生日晚會， 大家都想念你。

Shouldn’t have+過去分詞 形容某件事不該做但還是做了

例：

I shouldn’t have eaten so much cake!

我不應該吃這麼多蛋糕的!

You should not have gone out last night or you would have your homework finished by now.  

昨晚你不應該出去， 否則現在你的作業就已經作完了。

Could have，would have，should have常被縮寫成 could've，would've，should've
發音上有點像是 "of": could-of，would-of，should-of

另外日常生活中，我們會說 “would have…should have…could have”或 “woulda, shoulda, coulda”合在一起來說，形容後悔的事情。