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PAST FORM |
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The past form of a modal verb varies
according to meaning, that is to say, according to
ability, possibility, probability,
certainty, obligation or necessity. Let us
see: |
|
ABILITY |
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To talk about the present you use can: |
|
The psychologist
can advise
Julia. ►
ABILITY IN THE PRESENT |
|
To talk about the past you use could, was able to
or manage to: |
|
My best friend
was able to
get on with all sorts of people and
could make
friends easily. She even
managed to
make fierce dogs lick her hand. ►
ABILITY IN THE PAST |
|
Please note that could and was
able to are not completely interchangeable. If you want
to describe general ability in the past you may use
COULD or was able to. But if you want to
describe ability on a particular occasion you must
use WAS ABLE TO, managed to or succeeded in. |
|
Please, keep this chart in mind: |
|
1 |
GENERAL ABILITY IN THE
PAST |
|
|
►
could
/
was able to |
|
2 |
ABILITY ON A
PARTICULAR OCCASION |
|
|
►
was able to
/
managed to
/
succeeded in |
|
|
Roberto
could usually
run a marathon in five hours. |
|
|
▼ |
|
|
GENERAL ABILITY
IN THE PAST |
|
|
Last Monday he
was able to do
it in four hours. |
|
|
managed to do |
|
|
succeeded in doing |
|
|
▼ |
|
|
ABILITY ON A
PARTICULAR OCCASION |
|
POSSIBILITY –
PROBABILITY – CERTAINTY |
|
To talk about the present or future you use may,
might or could (possibility), will (probability),
or must (certainty). |
|
As an example, check out this dialogue at a party: |
|
MARIA: |
Mario is not very talkative,
Luis. He
may be shy,
and I
might make
him nervous, or he
could
be trying to make me jealous.
►
POSSIBILITY |
| LUIS: |
He
will speak to
you soon. ►
PROBABILITY |
|
|
He keeps looking at you,
Maria. I'm sure he
must want to
say something. ►
CERTAINTY |
|
|
To talk about the past you usually use the pattern MODAL
+ HAVE + PAST PARTICIPLE. You use would have,
might have and could have to talk about something
that was possible in the past, although it didn't actually
happen: |
|
Things
might have been
different between Mario and Christian.
Christian is ruining what
could have remained
a good friendship.
Mario would have
introduced him to some new ideas. |
|
You use may have, might have or could have
to say that it is possible something happened, but you don't
know whether it happened or not: |
|
As an example, check out this dialogue: |
|
SIMON: |
I don't know why Lucia is late. She
may have had
an accident. |
|
CARLO: |
Don't worry. She
might have stopped
to talk to a friend. She
could have
missed her train. |
|
|
You use must have and can't have to express
certainty about the past: |
|
It
can't have been
easy for Christian.
He must have
felt lonely when Mario went away. |
|
OBLIGATION
– NECESSITY |
|
To talk about the present you use ought to, should,
must and have to. |
|
Julia has to face facts. She
must find
another place for Maria in her life. But Maria
ought to change
as well. She should
try to grow up.
►
OBLIGATION IN THE PRESENT |
|
You use had to to express past obligation. |
|
Mario
had to go
away to college. ►
OBLIGATION IN THE PAST |
|
Ought to have and should have are used when
an obligation in the past is not completed, or when
something has been done that shouldn't have been done. |
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Complicated? Check out these 'funny' examples... and relax: |
|
You
ought to have told
me that this grammar was so complicated.
You shouldn't
have lied to me, Mr. Grammar. Now, I'm really angry
!! |
|
Didn't have to and didn't need to are used to
express lack or absence of obligation or necessity in the
past: |
|
OM Personal
didn't have to get
a visa to go to Chile and Uruguay.
They didn't
need to get a visa to visit Peru, Bolivia and Brazil.
But they needed a visa to go to Islas Malvinas !!
:–(
►
LACK OF NECESSITY IN THE PAST |
|
Needn't have expresses the idea that something
unnecessary was done: |
|
Mario and Christian aren't friends
any more.
This needn't have
happened. It could have been avoided, couldn't it? |
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On the next page you can practise this
grammar. |
