詞性
adj.完成的；做好了的；煮熟的；合乎禮儀（規矩）的；不再發生的；為社會所接受的（非正式）。
int.感歎詞，（表示接受建議）行，好
v.做（do 的過去分詞）
n. (Done) （美、英、羅馬尼亞）多恩（人名）
區别
簡介
“would+have+done”虛拟語氣，表示對過去事情的假設，意思是“本來會做”。
例句
1.I would have told you all about the boy's story, but you didn't ask me.我本來會告訴你這個小男孩的故事，但是你沒有問我。
2.Without your help,I wouldn't have achieved so much.沒有你的幫助，我是不會取得如此大的成績。
“could+have+done”是虛拟語氣，表示對過去事情的假設，意思是本來能夠做某事而沒有做。
He could have passed the exam, but he was too careless.本來他能夠通過考試，但是他太粗心。
相關知識
must+have+done
表示對過去事情的肯定推測，譯成“一定做過某事”，該結構隻用于肯定句。
1.It must have rained last night,for the ground is wet.昨晚一定下雨了，因為地面還是濕的。
2.You must have been mad to speak to the servant.你和仆人說話，一定是發瘋了。
can't+have+done
表示對過去事情的否定推測，譯成“不可能做過某事”。
1.Mr.Smith can't have gone to Beijing,for I saw him in the library just now.史密斯先生不可能去北京了，我剛才還在圖書館見過他。
2.Mary can't have stolen your money.She has gone home.瑪麗不可能偷你的錢，她回家去了。
can+have+done
表示對過去行為的懷疑，用于疑問句，譯成“可能做過……嗎？”。
1.There is no light in the room.Can they have gone out?屋裡沒有燈，他們可能出去了嗎？
2.There is nowhere to find them.Where can they have gone?到處找不到他們，他們可能到什麼地方去呢？
may+have+done
表示對發生過的事情的推測，意思是“可能已經”或“也許已經”，用于肯定句中。
—What has happened to George?
—I don't know. He may have got lost.
—喬治發生了什麼事？
——我不知道，他可能迷路了。
might+have+done
表示對過去事情的推測，might與may意思相同，但可能性更小。多用于虛拟語氣結構中。
1.He might have given you more help, even though he was busy.他或許會多給你一些幫助，即使他很忙。
2.She might have achieved greater progress, if you had given her more chances.如果你多給她點機會，她可能已經取得更大的成績。
should+have+done
意思是“本來應該做某事，而實際沒做。”“shouldn't+have+done”表示本來不應該做某事，而實際做了。含有指責對方或自責的含意。
1.Tom,you are too lazy.The work should have been finished yesterday.湯姆，你太懶惰了，這項工作本來應該昨天就做完的。
2.Look,Tom is crying. I shouldn't have been so harsh on him.看，湯姆哭了，我本來不應該對他如此嚴厲。
3 do you feel guilty when you have done something youshould"t.
ought to+have+done
表示過去應該做而實際并沒有做，譯成“理應做……”，往往表示遺憾。與“should+have+done”用法基本一樣。
I ought to have gone home last Sunday.我理應上星期日回家。
You ought not to have given him more help.你不應該幫助他那麼多。
need+have+done
表示本來需要做某事而沒有做。“needn't+have+done”則表示“本來不需要做某事而做了”。
I needn't have bought so much wine—only five people came.我本來沒有必要買這麼多酒，隻來了五個人。
He need have hurried to the station.In that case,be wouldn't have missed the train.他本來需要快點去車站，那樣的話，他就不會誤了火車。
would like to have done sth.本打算做某事
I would like to have read the article,but I was very busy then.
would rather +have done.當時甯願做了或沒做
I would rather have refuse his offele.
