這期我們要來(lái)學(xué)習(xí)情態(tài)動(dòng)詞+完成時(shí)的用法,當(dāng)然包括了大家最關(guān)心的虛擬語(yǔ)氣.
1. may和might+ 動(dòng)詞完成式
此結(jié)構(gòu)用于推測(cè)過(guò)去的行為。例如：
She said that he might have missed the plane.她說(shuō)他可能誤了航班。
2. can和could+ 動(dòng)詞完成式
A. 表示過(guò)去能做而沒(méi)做的事，有一種對(duì)過(guò)去未付諸實(shí)施的事情的惋惜。例如：
In those circumstances we could have done better.
在那樣的情況下，我們本來(lái)可以做得更好的。(但沒(méi)有做得更好)
B. 推測(cè)過(guò)去的某種行動(dòng)。
Where can /could she have gone? 她可能到哪里去了呢?
The boy can’t have finished reading the book so soon because it is difficult even to an adult.
這孩子不可能那么快就把這本書(shū)讀完的，因?yàn)榧词箤?duì)一個(gè)成人來(lái)說(shuō)，這本書(shū)也是相當(dāng)難的。
Note:
can’t和couldn’t+ 動(dòng)詞原形可以用來(lái)表示否定推斷。例如：
He can’t be over fifty.他不可能超過(guò)50歲。
3.must +動(dòng)詞完成式
表示對(duì)過(guò)去行為的推斷，具有較大的可能性，意為“一定…，想必…”。例如：
She must have gone through a lot.
她一定吃過(guò)很多苦。
Note:
must+動(dòng)詞原形→對(duì)現(xiàn)在的推測(cè)，must be+現(xiàn)在分詞→對(duì)未來(lái)或現(xiàn)在正在進(jìn)行的推測(cè)。例如：
She looks happy; she must be having a good time.
4. needn’t+動(dòng)詞完成式和didn’t need to do
A. needn’t+動(dòng)詞完成式表示一種已經(jīng)做過(guò)的但并無(wú)必要的行為。例如：
You needn’t have watered the flowers, for it is going to rain.
你本來(lái)不必澆花的，因?yàn)樘煲掠炅恕?但卻澆了)
We needn’t have told him the news because he knew it already.
B. didn’t need (have) to do結(jié)構(gòu)表示沒(méi)有必要做某事，實(shí)際上也沒(méi)有做。例如：
I didn’t need to clean the windows. My sister did it.
我不必擦窗，我妹妹擦了。(我沒(méi)有擦)
5. should +動(dòng)詞完成式
A.此結(jié)構(gòu)的肯定式表示應(yīng)該做的事而沒(méi)有做，否定式表示某種行為不該發(fā)生但卻發(fā)生了。例如：
You should have given her more help.
你應(yīng)該多給她一些幫助的。(但沒(méi)有給)
B. 表示推測(cè)，意為“可能”，但可能性較小。例如：
He should have finished the work by now.
他現(xiàn)在該把工作完成了。(推測(cè))
C. should / would have thought意為“本以為，本認(rèn)為”。例如：
A: "Can you type?"
B: "Certainly."
A: "Well, I should have thought you wouldn’t."
I should have thought she wouldn’t agree.
我本來(lái)認(rèn)為她不會(huì)同意的。
D. should have thought有時(shí)意為“認(rèn)為，以為”，相當(dāng)于should think，但表示更為委婉、謙遜或不肯定的語(yǔ)氣。例如：
I should have thought it fairly good.
我以為它是很不錯(cuò)的。
E. should have + 過(guò)去分詞用于虛擬語(yǔ)氣：
Had you written him, you should have known the details.
6. ought to + 動(dòng)詞完成式
此結(jié)構(gòu)表示某種過(guò)去應(yīng)該做而沒(méi)有做的事，或被忽略未做的某種明智行為。例如：
You ought to have returned the book earlier.(還晚了)
You ought to have refused her at the beginning, but now it is too late.
Note:
這里的ought to也可以用should代替。
Homework:用給出的動(dòng)詞填空,注意要選用正確的助動(dòng)詞和時(shí)態(tài).
1.The boy____ the book so soon because it is difficult even to an adult. (read)
2.We___him the news because he knew it already. (tell)
3.If we had taken the other road, we ____earlier. (arrive)
4.I _____you might take this into consideration. (think)
5.You ____ her at the beginning, but now it is too late.(refuse)
1. may和might+ 動(dòng)詞完成式
此結(jié)構(gòu)用于推測(cè)過(guò)去的行為。例如：
She said that he might have missed the plane.她說(shuō)他可能誤了航班。
2. can和could+ 動(dòng)詞完成式
A. 表示過(guò)去能做而沒(méi)做的事，有一種對(duì)過(guò)去未付諸實(shí)施的事情的惋惜。例如：
In those circumstances we could have done better.
在那樣的情況下，我們本來(lái)可以做得更好的。(但沒(méi)有做得更好)
B. 推測(cè)過(guò)去的某種行動(dòng)。
Where can /could she have gone? 她可能到哪里去了呢?
The boy can’t have finished reading the book so soon because it is difficult even to an adult.
這孩子不可能那么快就把這本書(shū)讀完的，因?yàn)榧词箤?duì)一個(gè)成人來(lái)說(shuō)，這本書(shū)也是相當(dāng)難的。
Note:
can’t和couldn’t+ 動(dòng)詞原形可以用來(lái)表示否定推斷。例如：
He can’t be over fifty.他不可能超過(guò)50歲。
3.must +動(dòng)詞完成式
表示對(duì)過(guò)去行為的推斷，具有較大的可能性，意為“一定…，想必…”。例如：
She must have gone through a lot.
她一定吃過(guò)很多苦。
Note:
must+動(dòng)詞原形→對(duì)現(xiàn)在的推測(cè)，must be+現(xiàn)在分詞→對(duì)未來(lái)或現(xiàn)在正在進(jìn)行的推測(cè)。例如：
She looks happy; she must be having a good time.
4. needn’t+動(dòng)詞完成式和didn’t need to do
A. needn’t+動(dòng)詞完成式表示一種已經(jīng)做過(guò)的但并無(wú)必要的行為。例如：
You needn’t have watered the flowers, for it is going to rain.
你本來(lái)不必澆花的，因?yàn)樘煲掠炅恕?但卻澆了)
We needn’t have told him the news because he knew it already.
B. didn’t need (have) to do結(jié)構(gòu)表示沒(méi)有必要做某事，實(shí)際上也沒(méi)有做。例如：
I didn’t need to clean the windows. My sister did it.
我不必擦窗，我妹妹擦了。(我沒(méi)有擦)
5. should +動(dòng)詞完成式
A.此結(jié)構(gòu)的肯定式表示應(yīng)該做的事而沒(méi)有做，否定式表示某種行為不該發(fā)生但卻發(fā)生了。例如：
You should have given her more help.
你應(yīng)該多給她一些幫助的。(但沒(méi)有給)
B. 表示推測(cè)，意為“可能”，但可能性較小。例如：
He should have finished the work by now.
他現(xiàn)在該把工作完成了。(推測(cè))
C. should / would have thought意為“本以為，本認(rèn)為”。例如：
A: "Can you type?"
B: "Certainly."
A: "Well, I should have thought you wouldn’t."
I should have thought she wouldn’t agree.
我本來(lái)認(rèn)為她不會(huì)同意的。
D. should have thought有時(shí)意為“認(rèn)為，以為”，相當(dāng)于should think，但表示更為委婉、謙遜或不肯定的語(yǔ)氣。例如：
I should have thought it fairly good.
我以為它是很不錯(cuò)的。
E. should have + 過(guò)去分詞用于虛擬語(yǔ)氣：
Had you written him, you should have known the details.
6. ought to + 動(dòng)詞完成式
此結(jié)構(gòu)表示某種過(guò)去應(yīng)該做而沒(méi)有做的事，或被忽略未做的某種明智行為。例如：
You ought to have returned the book earlier.(還晚了)
You ought to have refused her at the beginning, but now it is too late.
Note:
這里的ought to也可以用should代替。
Homework:用給出的動(dòng)詞填空,注意要選用正確的助動(dòng)詞和時(shí)態(tài).
1.The boy____ the book so soon because it is difficult even to an adult. (read)
2.We___him the news because he knew it already. (tell)
3.If we had taken the other road, we ____earlier. (arrive)
4.I _____you might take this into consideration. (think)
5.You ____ her at the beginning, but now it is too late.(refuse)