1、情態(tài)動(dòng)詞后面加不定式的完成式，即“情態(tài)動(dòng)詞+ have + done”，用來(lái)表示過(guò)去時(shí)間的各種情態(tài)。用法如下：
用在句子中，對(duì)過(guò)去的行為或過(guò)去的行為或動(dòng)作的推測(cè)、評(píng)論或判斷，表示某種事情“一定”“可能”或“應(yīng)該”已經(jīng)完成或發(fā)生了?？忌鷳?yīng)該牢記不同的情態(tài)動(dòng)詞與不定式完成式連用所表達(dá)的意思。如：wouldn’t have done sth （本來(lái)不會(huì)…）should/ought to have done sth.（本應(yīng)/應(yīng)該已經(jīng)…），shouldn’t/oughtn’t to have done sth.(本不該…)，would have done sth （本來(lái)會(huì)…）can/could/may/might have done sth.(可能已經(jīng)/也許已經(jīng)…)，must have done sth.(一定/準(zhǔn)時(shí)/準(zhǔn)是…)，can’t/couldn’t have done sth.(一定沒(méi)/準(zhǔn)沒(méi)有…)。Needn’t + 完成式表示對(duì)已經(jīng)做過(guò)的事感到是不必要的。
例：I could have arrived a little earlier, but I met a friend of mine on the way.
The children must have got terrified in last night’s earthquake.
Since they aren’t answering the telephone, they must have left.
You needn’t have told her again because she has a good memory.
You needn’t have interrupted the class to tell me that; you could have come up to me afterwards.
2、情態(tài)動(dòng)詞后面加進(jìn)行時(shí)，即“情態(tài)動(dòng)詞 + be + doing”，表示“應(yīng)當(dāng)正在…”、“想必/一定正在…”、“可能/也許正在…”等意思。情態(tài)動(dòng)詞后面加上完成進(jìn)行式，即“情態(tài)動(dòng)詞 + have been doing”，表示“應(yīng)當(dāng)一直在…”、“想必一直在…”等意思。
例：He shouldn’t be watching TV now. It’s time for class.
The president of our company isn’t here. He may be interviewing candidates for the post of sales manager at the moment.
The economy seems to be sluggish these days.
He said he could drink a bottle of whisky. He must be joking.
They must haven been working on their thesis.
3、情態(tài)動(dòng)詞后面的被動(dòng)語(yǔ)態(tài)。在很多情況下，動(dòng)詞的主語(yǔ)是動(dòng)作的承擔(dān)者，因此，是有情態(tài)動(dòng)詞的句子，情態(tài)動(dòng)詞后面就要跟動(dòng)詞的被動(dòng)語(yǔ)態(tài)形式。
例：The Central Park can be seen from the top of this exclusive apartment building.
Many rare animals should be saved from extinction.
The girl must have been frightened by the thrilling movie in which there are some violent scenes.
用在句子中，對(duì)過(guò)去的行為或過(guò)去的行為或動(dòng)作的推測(cè)、評(píng)論或判斷，表示某種事情“一定”“可能”或“應(yīng)該”已經(jīng)完成或發(fā)生了?？忌鷳?yīng)該牢記不同的情態(tài)動(dòng)詞與不定式完成式連用所表達(dá)的意思。如：wouldn’t have done sth （本來(lái)不會(huì)…）should/ought to have done sth.（本應(yīng)/應(yīng)該已經(jīng)…），shouldn’t/oughtn’t to have done sth.(本不該…)，would have done sth （本來(lái)會(huì)…）can/could/may/might have done sth.(可能已經(jīng)/也許已經(jīng)…)，must have done sth.(一定/準(zhǔn)時(shí)/準(zhǔn)是…)，can’t/couldn’t have done sth.(一定沒(méi)/準(zhǔn)沒(méi)有…)。Needn’t + 完成式表示對(duì)已經(jīng)做過(guò)的事感到是不必要的。
例：I could have arrived a little earlier, but I met a friend of mine on the way.
The children must have got terrified in last night’s earthquake.
Since they aren’t answering the telephone, they must have left.
You needn’t have told her again because she has a good memory.
You needn’t have interrupted the class to tell me that; you could have come up to me afterwards.
2、情態(tài)動(dòng)詞后面加進(jìn)行時(shí)，即“情態(tài)動(dòng)詞 + be + doing”，表示“應(yīng)當(dāng)正在…”、“想必/一定正在…”、“可能/也許正在…”等意思。情態(tài)動(dòng)詞后面加上完成進(jìn)行式，即“情態(tài)動(dòng)詞 + have been doing”，表示“應(yīng)當(dāng)一直在…”、“想必一直在…”等意思。
例：He shouldn’t be watching TV now. It’s time for class.
The president of our company isn’t here. He may be interviewing candidates for the post of sales manager at the moment.
The economy seems to be sluggish these days.
He said he could drink a bottle of whisky. He must be joking.
They must haven been working on their thesis.
3、情態(tài)動(dòng)詞后面的被動(dòng)語(yǔ)態(tài)。在很多情況下，動(dòng)詞的主語(yǔ)是動(dòng)作的承擔(dān)者，因此，是有情態(tài)動(dòng)詞的句子，情態(tài)動(dòng)詞后面就要跟動(dòng)詞的被動(dòng)語(yǔ)態(tài)形式。
例：The Central Park can be seen from the top of this exclusive apartment building.
Many rare animals should be saved from extinction.
The girl must have been frightened by the thrilling movie in which there are some violent scenes.