Collins Cobuild English Grammar (114 page)

formal permission:
may

5.141
   In more formal situations,
may
is used to give permission.

You
may
speak now.
They
may
do exactly as they like.

permission in the past:
could

5.142
   
Could
is used to say that someone was allowed to do something in the past.

We
could
go to any part of the island we wanted to.

BE CAREFUL

5.143
   You cannot use
can
or
could
to say that someone will be allowed to do something in the future. Instead you use
be able to
.

Be able to
is dealt with in paragraphs
5.222
to
5.229
.

Saying that something is unacceptable

5.144
   Modals are often used in negative structures to say that an action is forbidden or unacceptable.

saying that something is forbidden:
cannot

5.145
   
Cannot
is used to say that something is forbidden, for example because of a rule or law.

Children
cannot
bathe except in the presence of two lifesavers.
We’re awfully sorry we
can’t
let you stay here.

saying that something is forbidden:
may not

5.146
   
May not
is used in a similar way to
cannot
, but is more formal.

You
may not
make amendments to your application once we have received it.
This material
may not
be published, broadcast, or redistributed in any manner.

saying that something is forbidden:
will not

5.147
   
Will not
is used to tell someone very firmly that they are not allowed to do a particular thing. Usually, the speaker has the power to prevent the hearer from doing this thing.

‘I’ll just go upstairs.’ – ‘You
will not
.’
Until we have cured you, you
won’t
be leaving here.

saying that something is forbidden:
shall not

5.148
   
Shall not
is used to say formally that a particular thing is not allowed.
Shall not
is often used in written rules, laws, and agreements.

Persons under 18
shall not
be employed in nightwork.
Equality of rights under the law
shall not
be denied or abridged by the United States or by any State.

Shan’t
is used in a similar way to
will not
and
won’t
.

You
shan’t
leave without my permission.

saying that something is forbidden: imperatives

5.149
   You can also say that something is not allowed by using an
imperative
sentence. Imperative sentences are explained in paragraph
5.4
and in paragraphs
5.35
to
5.39
.

undesirable actions:
should not

5.150
   
Should not
is used to tell someone that an action is unacceptable or undesirable.

You
should not
take her help for granted.
You
shouldn’t
do that.
You
shouldn’t
be so unfriendly.

undesirable actions:
must not

5.151
   
Must not
is used to say much more firmly that something is unacceptable or undesirable.

You
must not
accept it.
You
mustn’t
do that.
You
mustn’t
breathe a word of this to anyone.

Interacting with other people

5.152
   You often say things in order to get someone to behave in a particular way. For example, you may want someone to take a particular action, to accept an offer, or to give their permission for something to be done.

In these situations, modals are often used. The modal you choose depends on several factors. The main ones are:

the formality or informality of the situation

the relationship between yourself and the person you are speaking to

the degree of politeness you want to show.

In particular situations, other factors can be important. For example, if you are making an offer or suggestion, the modal you choose may depend on how persuasive you want to be.

5.153
   The following sections explain how to use modals in different situations.

Paragraphs
5.154
to
5.170
explain how to give instructions and make requests.

Paragraphs
5.171
to
5.179
explain how to make an offer or an invitation.

Paragraphs
5.180
to
5.187
explain how to make suggestions.

Paragraphs
5.188
to
5.193
explain how to state an intention.

Paragraphs
5.194
to
5.199
explain how to express unwillingness or a refusal to do something.

Paragraphs
5.200
to
5.208
explain how to express a wish.

Paragraphs
5.209
to
5.213
explain how to indicate the importance of doing something.

Paragraphs
5.214
to
5.220
explain various ways of introducing what you are going to say.

Giving instructions and making requests

5.154
   When you give an instruction or make a request, you usually use a modal in an interrogative sentence.

You use
will
,
would
,
can
, or
could
with
you
to tell someone to do something, or to ask someone to do something.

You use
can
,
could
,
may
, or
might
with
I
or
we
or with other personal pronouns or noun phrases to ask someone’s permission to do something.

Instructions and requests are always made more polite by adding
please
.
Please
and other markers of politeness are explained in paragraph
5.170
.

instructions and appeals for help

5.155
   
Will
,
would
, and
could
are used with
you
in two ways:

you use them to give an instruction or an order

you use them to ask for help or assistance.