ought to后面接完成式表示本應(yīng)該發(fā)生或本應(yīng)該做的事而沒有發(fā)生或沒有做；它的否定形式則表示本不應(yīng)該發(fā)生或本不應(yīng)該做的事而已經(jīng)發(fā)生或已經(jīng)做了。例如：
They ought to have completed their work much earlier.
他們本應(yīng)該在更早一些的時(shí)候完成他們的工作的。
You oughtn't to have left your keys in the office when you went out.
你不該出去的時(shí)候?qū)㈣€匙留在辦公室里。
I ought to have said it to her in a calmer mood.
我應(yīng)該以更平靜一些的語氣對她說那件事的。
need后面接完成式主要用于否定句中，表示不必要做的事而已經(jīng)做了。例如：
We needn't have read the Fast Reading materials before we do it in class.
我們在做快速閱讀練習(xí)之前沒有必要把閱讀材料先看過了。
You needn't have apologized to him for nothing yesterday.
你昨天沒有必要無為地向他道歉。
should后面接完成式表示本應(yīng)該發(fā)生或本應(yīng)該做的事而沒有發(fā)生或沒有做；它的否定形式則表示本不應(yīng)該發(fā)生或本不應(yīng)該做的事而已經(jīng)發(fā)生或已經(jīng)做了。例如：
I should have written to you earlier. But I've really been busy.
我本應(yīng)該早就給你寫信的；不過我真的一直都很忙。
You shouldn't have left your son alone at home.
你不該將你兒子一個(gè)人留在家里的。
He shouldn't have broken the red light.
他不該闖紅燈的。
They ought to have completed their work much earlier.
他們本應(yīng)該在更早一些的時(shí)候完成他們的工作的。
You oughtn't to have left your keys in the office when you went out.
你不該出去的時(shí)候?qū)㈣€匙留在辦公室里。
I ought to have said it to her in a calmer mood.
我應(yīng)該以更平靜一些的語氣對她說那件事的。
need后面接完成式主要用于否定句中，表示不必要做的事而已經(jīng)做了。例如：
We needn't have read the Fast Reading materials before we do it in class.
我們在做快速閱讀練習(xí)之前沒有必要把閱讀材料先看過了。
You needn't have apologized to him for nothing yesterday.
你昨天沒有必要無為地向他道歉。
should后面接完成式表示本應(yīng)該發(fā)生或本應(yīng)該做的事而沒有發(fā)生或沒有做；它的否定形式則表示本不應(yīng)該發(fā)生或本不應(yīng)該做的事而已經(jīng)發(fā)生或已經(jīng)做了。例如：
I should have written to you earlier. But I've really been busy.
我本應(yīng)該早就給你寫信的；不過我真的一直都很忙。
You shouldn't have left your son alone at home.
你不該將你兒子一個(gè)人留在家里的。
He shouldn't have broken the red light.
他不該闖紅燈的。