We can use modal verbs to talk about how sure
or unsure we are about something in the past just as we use modals in the
present with a slight change in the form.
He must be really happy about his
promotion. (present deduction)
He must have been very happy when he
was told about his promotion. (past deduction)
STRONG PROBABILITY
Must
MODERATE PROBABILITY
Could
Might
May
STRONG IMPROBABILITY
Couldn't
Must not
When we use a modal verb to talk
about a situation where we are not expressing a fact but we are using deduction
the form is MODAL + have + past participle (verb 3)
Must have + past participle
We
use ‘must have + past participle’ when we are quite sure about something.
You
must have been very pleased when you received the results of your exams.
He
must have forgotten his phone at home again. He’s not answering.
I
must have left my keys in the car. I can’t find them.
Might have/may have/could have +
past participle
We
use ‘might have/may have/could have + past participle’ when we are not sure
about something but we think it was possible.
He
was supposed to be here an hour ago but he could have been stuck in a traffic
jam.
He
may have said he was coming but I can’t really remember. I wasn’t listening.
I
might have been here when I was a child but I can’t really remember.
Can’t have + past participle
We
use ‘can’t have + past participle’ for things that we are sure did not happen
in the past.
I
can’t have left my phone at work. You phoned me when I was walking to my car.
That’s it. It must be in the car.
You
can’t have seen him this morning. He was with me all the time.
She
can’t have liked the show. She hates musicals.
First, we mean general ability. This is something that once you have learned you can do any time you want, like being able to read or swim or speak a language, for example.
The other kind of ability is specific ability. This mean something that you can or can't do in one particular situation. For example, being able to lift something heavy, or find somewhere you are looking for.
VERB + INFINITIVE
be able
I manage
VERB + BASE FORM
can / can't
could / couldn't
verb + gerund
VERB + GERUND
be capable of
be incapable of
be good at
succed in
COULD
Could can be used in many different ways, to
ask for permission, to make a request or to express ability when referring to
the past. Was able to is sometimes used as an alternative to could when we are
discussing ability or possibility. We tend to use could when we are talking
about ability generally. Compare the following:
By
the time she was seven, she could already speak three languages.
She
started the viola at the age of eight and after only six months she could play
it quite well.
Her
brother Jack was an excellent swimmer. He could beat anybody in his class.
WAS ABLE TO / MANAGED TO
We tend to use was able to or managed to if we
are talking about what happened in a particular situation or are referring to a
specific achievement:
Were
you able to / Did you manage to speak to him before he left home?
~
No, I'm sorry, I wasn't able to / didn't manage to reach him.
The
fog came down and I wasn't able to / didn't manage to get to the top of the
mountain.
My
brother wanted to carry on, but we managed to / were able to talk him out of
it.
However, with verbs that refer to the five
senses, see, hear, smell, feel, taste, and with verbs that refer to thought
processes, understand, believe, remember, decide, we normally use could, even
when we are talking about specific occasions:
He
was standing very close to me and I could smell the garlic on his breath.
He
asked me when Julie's birthday was, but I couldn't remember.
I
couldn't decide whether to ask him for a lift or not.
I
could see that he'd been running.
UNABLE TO / NOT SUCCEED IN
Note that unable to is an alternative negative
form of not able to and succeed in is a slightly more formal alternative to
manage to. But remember that succeed in is followed by verb + ing, rather than
verb + infinitive:
We
were unable to leave the room until the locksmith arrived and succeeded in
unlocking the door.
I
was unable to complete the report as several pieces of information were
missing.
Having
obtained them, I succeeded in completing it after a further two days.
BE ABLE TO
Note that can has no infinitive form, no -ing
form, no perfect form and no future form. It cannot follow another modal
auxiliary verb. On all of these occasions, we have to use be able to instead.
Compare the following:
I'd
like to be able to swim like Jack. He swims like a fish.
When
I'm at the sea-side, I enjoy being able to take a swim every morning.
Unfortunately,
Jack hasn't been able to swim since his accident.
Lets'
hope he'll be able to resume his daily swimming training soon.
I'm not a member, but can I swim in this pool?
~ Why don't you speak to the secretary? She may / might / should be able to
help you.
MANAGE = SUCCEED / COPE
We use the verbs manage to and manage a great
deal in current English when we want to say that we are able to cope with a difficult
situation or find time for a particular task. Compare the following:
It
was very icy, but I managed to keep the car on the road.
Veronica
was very upset when Ben left her, but she managed to smile nevertheless.
She
didn't really want to go to Mexico, but Tony managed to persuade her somehow.
Can
you help me put up my new shed? ~ I can manage a few hours in the morning, but
I'm busy in the afternoon.
This
is an ideal job for those who can only manage a few hours each week.
Can
I give you a hand with that? ~ No, it's all right. I'll manage./ I can
manage.
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