Collins Cobuild English Grammar (112 page)

The use of modals to express a refusal is explained in paragraphs
5.194
to
5.199
.

Talking about possibility

5.115
   The following four sections explain the different ways in which modals are used to talk about the possibility of something happening or being done.

Paragraphs
5.116
to
5.119
explain how
can
and
could
are used to talk about the ability of a person or thing to do something.

Paragraphs
5.120
to
5.139
explain how modals are used to express degrees of certainty about past, present, and future situations and events.

Paragraphs
5.140
to
5.143
explain how modals are used to say that something is permissible.

Paragraphs
5.144
to
5.151
explain how modals are used to say that something is forbidden or unacceptable.

Talking about ability

skills and abilities:
can
and
could

5.116
   
Can
is used to say that someone has a particular skill or ability.

You
can
all read and write.
Some people
can
ski better than others.
He
cannot
dance. …the girl who
can’t
act.

Could
is used to say that someone had a skill or ability in the past.

When I arrived, I
could
speak only a little English.
I
could
barely walk.
He
could
kick goals from anywhere.

awareness:
can
and
could

5.117
   
Can
is also used to say that someone is aware of something through one of their senses.

I
can
see you.
I
can
smell it.
Can’t
you?

Could
is used to say that someone was aware of something through one of their senses on a particular occasion in the past.

I
could
see a few faint stars in a clear patch of sky.
I
could
feel my heart bumping.
Police said they
could
smell alcohol on his breath.

general truths:
can
and
could

5.118
   
Can
and
could
are also used to express facts that are generally the case, particularly when they relate to something or someone being capable of having a particular effect, or of behaving in a particular way.

It
can
be very unpleasant.
Art
can
be used to communicate.
Throwing parties
can
be hard work.
He
could
be very stiff, could Haggerty.
He
could
really frighten me, and yet at the same time he
could
be the most gentle and courteous of men.

BE CAREFUL

5.119
   You cannot use
can
or
could
to say that someone or something will have a particular ability in the future. Instead you use
be able to
or
be possible to
.

Be able to
and
be possible to
can also be used to talk about someone’s ability to do something in the present or the past.

Be able to
and
be possible to
are dealt with in paragraphs
5.222
to
5.229
.

Talking about likelihood

5.120
   The following paragraphs explain how modals are used to express different degrees of certainty about past, present, and future situations and events.

Paragraphs
5.121
to
5.127
explain the main ways in which modals are used to express degrees of certainty.

Paragraphs
5.128
to
5.132
explain special uses of modals when talking about possible future situations.

Paragraphs
5.133
to
5.139
explain special uses of modals when talking about possible situations in the past.

assuming that something is the case:
will
and
would

5.121
   You use
will
when you are assuming that something is the case, and you do not think there is any reason to doubt it.

Those of you who are familiar with the game
will
know this.
He
will
be a little out of touch, although he’s a rapid learner.
She
will
have forgotten all about it by now.

Similarly, you use
will not
or
won’t
when you are assuming that something is not the case.

The audience
will not
be aware of such exact details.
You
won’t
know Gordon. He’s our new doctor.

After
you
, you can use
would
instead of
will
, if you want to be more polite.

You
would
agree that the United States should be involved in assisting these countries.

certainty:
would
and
should

5.122
   You also use
would
to say that something is certain to happen in particular circumstances.

Even an illiterate person
would
understand that.
Few people
would
agree with this as a general principle.
A picnic
wouldn’t
be any fun without you.

After
I
, you can use
should
instead of
would
.

The very first thing I
should
do would be to teach you how to cook.
I
should
be very unhappy on the continent.

This is unusual in American English, which normally uses
would
after
I
.

belief:
must
and
cannot

5.123
   You use
must
to show that you believe something is the case, because of particular facts or circumstances.

Oh, you
must
be Sylvia’s husband.
Fashion
must
account for a small percentage of sales.
This article
must
have been written by a woman.

When you are indicating that something is not the case, you use
cannot
. You do not use
must not
. (See paragraph
5.126
.)

The two conflicting messages
cannot
possibly both be true.
You
can’t
have forgotten me.
He
can’t
have said that. He just
can’t
.

present possibility:
could
,
might
, and
may

5.124
   You use
could
,
might
, or
may
to say that there is a possibility of something happening or being the case.
May
is slightly more formal than
could
or
might
; otherwise there is very little difference in meaning between these modals.

Don’t eat it. It
could
be poisonous.
His route from the bus stop
might
be the same as yours.
In rare cases the jaw
may
be broken during extraction.

If you put
well
after
could
,
might
, or
may
, you are saying that it is fairly likely that something is the case.

It
could well
be that the economic situation is getting better.
His predictions
could well
have come true.
You
might well
be right.
I think that
may well
have been the intention.

negative possibility:
might not
and
may not

5.125
   You use
might not
or
may not
to say that it is possible that something is not the case.

He
might not
be in England at all.
That
mightn’t
be true.
That
may not
sound very imposing.

impossibility:
could not
and
cannot

5.126
   You use
could not
or
cannot
to say that it is impossible that something is the case.