Collins Cobuild English Grammar (118 page)

5.212
   
Shall have to
is sometimes used instead of
will have to
after
I
or
we
.

I
shall have to
speak about that to Peter.
We
shall have to
assume that you are right.

This is a slightly formal use, and is rarely used in American English.

importance:
should
and
ought to

5.213
   
Should
and
ought to
are used in three different ways when you are talking about the importance of doing something.

You use
should
or
ought to
when you are trying to help someone by advising them to do something.

Carbon steel knives
should
be wiped clean after use.
You
should
claim your pension 3-4 months before you retire.
You
ought to
try a different approach.

You use
should
or
ought to
when you are saying that something is the right or correct thing to do.

We
should
send her a postcard.
The judges
should
offer constructive criticism.
We
ought to
stay with him.
You
ought
not
to
do that.

You use
should
or
ought to
with
have
and an
-ed
participle to say that something was desirable in the past, although it did not in fact happen.

One sailor
should have
been asleep and one on watch.
We
ought to have
stayed in tonight.
A more junior member of staff
ought to have
done the work.

You also use
should
and
ought to
to say that you expect something to happen. This use is explained in paragraph
5.131
.

Introducing what you are going to say

5.214
   Sometimes you introduce what you are going to say by using a modal followed by a verb such as
say
or
ask
that refers to the act of saying something. You can also combine a modal with a verb such as
think
or
believe
that refers to the holding of an opinion.

You use a modal in order to sound more polite, or to show your feelings about what you are going to say.

In structures like these, the subject is usually
I
. Sometimes you use an impersonal structure beginning with
it
or
you
. For example, instead of saying
I ought to mention that he had never been there
, you can say
It ought to be mentioned that he had never been there
.

importance:
must

5.215
   If you feel strongly that what you are saying is important, you use
must
.

I
must
apologize to you.
I
must
object.
It
must
be said that he has a point.

importance:
should
and
ought to

5.216
   If you feel that it is important or appropriate that something is said, you indicate that you are going to say it by using
should
or
ought to
.

I
should
explain at this point that there are two different sorts of microscope.
It
should
also be said that I learned a great deal from the experience.
I
ought to
stress that this was not a trial.
Perhaps I
ought to
conclude with a slightly more light-hearted question.

politeness:
can
and
could

5.217
   If you want to say something during a discussion, you can indicate politely that you are going to say it by using
can
.

Perhaps I
can
mention another possibility.
If I
can
just intervene for one moment…

If you want to be even more polite, you use
could
.

Perhaps I
could
just illustrate this by mentioning two cases that I know of personally.
Perhaps I
could
just ask you this…

5.218
   You also use
can
and
could
when you are mentioning an opinion or a way of describing something.

Can
suggests that you approve of the opinion or description.

Such behaviour
can
be a reaction to deep emotional upset.

Could
is more neutral.

You
could
argue that this is irrelevant.
You
could
call it a political offence.

approval:
may
and
might

5.219
   
May
and
might
can also be used to mention an opinion or a way of describing something.

May
suggests that you approve of the opinion or description. It is more formal than
can
.

This, it
may
be added, greatly strengthened him in his resolve.

Might
also suggests that you approve of the opinion or description. You use
might
when you think there is a possibility that the person you are talking to will disagree with you.

You
might
say she’s entitled to get angry.
That, one
might
argue, is not too terrible.

politeness:
should
and
would

5.220
   If you are stating an opinion of your own, you can show politely that you are going to state it by using
should
.

I
should
think it would last quite a long time.

Would
is used in a similar way, but is less common.

I
would
guess it may well come down to cost.

Expressions used instead of modals

5.221
   Several ordinary verbs and fixed expressions are used to express the same attitudes and ideas as modals. These verbs and expressions are explained in the following paragraphs. Each group of paragraphs corresponds to an earlier section in the chapter dealing with the use of modals in a particular type of situation.

saying whether something is possible

5.222
   
Be able to
and
be possible to
can be used instead of
can
and
could
to say whether or not something is possible.

The subject of
be able to
and
be unable to
usually refers to a person or group of people, but it can refer to any living thing. It can also refer to something organized or operated by people, such as a company, a country, or a machine.

The subject of
be possible to
is always the impersonal pronoun
it
.

5.223
   If you want to say that it is possible for someone or something to do something, you can use
be able to
.

All members
are able to
claim travelling expenses.
The college
is able to
offer a wide choice of subjects.

You use
be able to
with a negative to say that it is not possible for someone or something to do something.

They
are not able to
run fast or throw a ball.

5.224
   You also use
be unable to
to say that it is not possible for someone or something to do something.

I am having medical treatment and
I’m unable to
work.
We
are unable to
comment on this.

5.225
   You also use
be possible to
with
it
as the subject to say that something is possible. You usually use this expression to say that something is possible for people in general, rather than for an individual person.

It
is possible to
insure against loss of earnings.
Is
it
possible to
programme a computer to speak?

If you use
be possible to
to say that something is possible for a particular person or group, you put
for
and a noun phrase after
possible
.

It is possible
for us to
measure his progress.
It’s possible
for each department to
support new members.

You use
be possible to
with a negative to say that something is not possible.

It
is not possible to
quantify the effect.

5.226
   You can also use
be impossible to
to say that something is not possible.

It
is impossible to
fix the exact moment in time when it happened.
It
is impossible
for him
to
watch TV and talk.

5.227
   To change the tense of
be able to
,
be unable to
,
be possible to
, or
be impossible to
, you simply change the form of
be
to an appropriate simple form.

The doctor
will be able to
spend more time with the patient.
Their parents
were unable to
send them any money.
It
was not possible to
dismiss his behaviour as a contributing factor.
It
was impossible
for her
to
obey this order.