学习重点：modal Auxliaries in the past 情态动词的过去式
Some Used of Modals in the Past 情态动词过去时的一些用法
Modal Auxiliaries in the Past 情态动词的过去时
情态动词的过去时可以用have和过去分词表示：
我们来把一些情态动词的现在形式和其过去形式做一下对照。下个单元里会列举其他的情态动词。
*这里的have一般不发/hQv/音，而发/hEv/和/Ev/音
（/hEv/只用在肯定句里）。
现在 肯定句
|
主语 |
情态动词 |
不定式 |
|
Ｉ
We
You
They
He/She/It |
may
might
could
would
should |
do it.
ask him.
|
|
ought to |
现在 否定句（缩略形式）
|
主语 |
情态动词 |
不定式 |
|
Ｉ
We
You
They
He/She/It |
may not
might not(mightn’t)
could not(couldn’t)
would not(wouldn’t)
should not(shouldn’t) |
do it.
ask him.
|
|
ought not to(oughtn’t to) |
现在 疑问句
|
情态动词 |
主语 |
|
不定式 |
|
May
Might
Could
Would
Could
Would
Should
Ought |
I
we
you
they
he/she/it |
to |
do it?
ask him?
|
过去 肯定句
|
主语 |
情态动词 |
have |
不定式 |
|
Ｉ
Ｗe
You
They
He/She/It |
May
Might
Could
Would
should |
have
|
Done it.
Asked him.
|
|
Ought to |
过去 否定句
|
主语 |
情态动词 |
have |
不定式 |
|
I
We
You
They
He/She?it |
May not
Might not(mightn’t)
Could not(couldn’t)
Would not(wouldn’t)
Should not(shouldn’t)
Ought not to(oughtn’t to) |
have
|
done it.
Asked him.
|
过去 疑问句
|
情态动词 |
主语 |
|
have |
不定式 |
|
May
Might
Could
Would
Should |
I
we
you
they
he/she/it |
|
have
|
done
asked him?
|
|
Ought |
to |
Some Yses of Modal in the Past 情态动词过去时的一些用法
must have can’t have
●如第３单元所说，以过去事实为基础进行推测时可以用must have(肯定)和can’t have(否定)
When did we last meet?我们上次见面是什么时候？
-It must have been before 1990, because I got married in 1990.一定是１９９０年之前，因为我１９９０年结的婚。
The woman I saw was wearing pink trousers.我看见的那个女人穿着一条粉色的裤子。
-It can’t have been my wife. She never weras pink.那一定不是我妻子，她从来不穿粉色的衣服。
May have 和might have表示“过去可能发生了某事，但不确定”。
-I don’t know. She may/might have gone home.我不知道。她可能已经回家了。
Why hasn’t John arrived yet?为什么约翰还没有来？
-He may/might have got lost.他可能迷路了。
●might have还可以对过去发生的事情，以假设为基础，对其结果进行推测。
Why didn’t you eeeeeeeeeeeenter the competition? You might have won.你为什么不参加比赛呢？你会羸。
Why did you jump/ You might have been killed.你为什么不跳开？你差点儿被杀。
may have就没有这种意思。
could have
could have有许多用法。
●可以像might have那样，表示“过去可能发生的某事，但不确定”。
Where’s Ann?安在哪儿？
-I don’t know. She could have gone home. 我不知道，她可能回家了。
●could have还可以像might have那样，对过去没有发生的事情，以假设为基础，对其结果进行推测。
You could have won.你可能会羸。
You could have been killed.你可能会被杀害
●couldn’t have表示过去“不可能发生某事”。
John couldn’t have killed the old woman. He was here with me.约翰不可能杀死那个老妇人。 他那时和我在一起。
should have和 ought have
●should have 和ought have表示“本来是做某事最好的方法，结果却没有做”。
I should have given him some money. ( but I didn’t. ) 我本应该给他一些钱。（但是我没有给）
I ought to have told him he was an idiot, ( but I didn’t ).
我应该告诉他，他是一个白痴。（但是我没有说）
You shouldn’t have talked to her, ( but you did ).你本不应该对他说。（但是我告诉了她）
You oughtn’t to have had a cigarette. (but you did).你本不应该吸烟。（但是你吸了）
●should have 和ought to have 还可以表示预计的事情没有发生，但到底会不会发生自己也不知道。
Where are we?We ought to have seen signs to London by now.我们要在哪儿？现在我们应该看见到伦敦的路标了。
It’s 9:30.John should have arrived by now.现在是９点半。约翰应该已经到了。
