Grammar reference

Modal verbs

What are they?

Modal auxiliary verbs are can, could, may, might, shall, should, will, would, must and ought to.

They are used before other verbs to add meaning, like certainty or obligation, to these verbs.

  • I can swim.
  • She will be very happy.
  • You must arrive early.

Review of modal verbs:

Affirmative

I/you/he/she/it/we/they can
could
may
might
shall
should
will
would
must
ought to

visit.

Negative

I/you/he/she/it/we/they can't
couldn't
mightn't
may not
shall not
shouldn't
won't
wouldn't
mustn't
*oughtn't to

visit.

*Ought to is not normally used in negative sentences.

Question

Can
Could
May
Might
Shall
Should
Will
Would
Must 		I/you/he/she/it/we/they

visit?

Ought I/you/he/she/it/we/they

to visit?

Modal verbs can be used:

  • to talk about possibility and to speculate, e.g. about the future
  • to express ability, obligation, permission, advice, etc.

Possibility

  • You could be experiencing the first symptoms of RSI.
  • He might be in the kitchen.
  • Using a mouse can cause problems.
  • That may be John at the door.

Certainty

  • The train must be late.
  • You must be joking!

Ability

  • She's only five, but she can ride a bike.
  • Can you touch your toes?

Requests

  • Can you help me to do my homework?
  • Could you open the window, please?

Advice

  • You should eat lots of fruit and vegetables.
  • You shouldn't go to bed so late.

Future

  • Study hard or you'll fail your exams.
  • Take an umbrella - it might rain.

Obligation

  • You must pay before you enter.

Prohibition

  • You mustn't smoke here.
  • You can't park your car here.

Permission

  • The ball can bounce only once.
  • You can leave when you want to.

Deduction

  • He ought to be there by now.
  • He might be ill today.

Modal verbs are followed by the base form of a verb (except ought, which is followed by to).

  • You can see the coast from here.
  • They might be late for the meal.
  • You ought to be more careful.
    NOT: You can to see the coast from here.

Do not add an -s to a modal verb in the third person singular.

  • He should go to the dentist.
    NOT: He shoulds go to the dentist.

Modal verbs do not need the auxiliary do in the negative and question forms.

  • You mightn't arrive in time to see me.
  • He wouldn't buy an expensive car
  • Should I take notes?
  • Can you take me to school today?
    NOT: Do you can take me to school today?