MODAL VERBS

What is a modal verb?

The modal verbs in English grammar are can, could, may, might, must, need not, shall/will, should/ought to. They express things like ability, permission, possibility, obligation etc. Modal verbs only have one form. They do not take -s in the simple present and they do not have a past simple or past participle form. However, some modal verbs have alternative forms that allow us to express the same ideas in different tenses.

Learn about the usage of modal verbs and their alternative forms in English grammar with Lingolia’s online lesson. Then put your knowledge to the test in the interactive exercises.

Conjugation of English Modal Verbs

There are a few points to consider when using modal verbs in a sentence:

• Modal verbs are generally only used in the present tense in English but we don’t add an -s in the third person singular.

  Example:

  He must do what he is told.
  (not: He musts …)

• Modal verbs do not take an auxiliary verb in negative sentences and questions.

  Example:

  Max need not worry about his future.
  Max must not touch any dangerous equipment.
  Can Max change a tyre?

• We always use modal verbs with a main verb (except for short answers and question tags). The main verb is used in the infinitive without to.

  Example:

  Max can change tyres.
  (not: Max can to change tyres.) 

Usage

We use modal verbs to express ability, to give advice, to ask for and give permission, to express obligation, to express possibility, to deduce and to make predicitions.

Can/Could for Ability

modal verb	alternative form
can/could	to be able to

We use can in simple present.

Example:

Max can already change a tyre.

We can use the alternative form to be able to in all tenses (present, past, perfect, progressive and future).

Example:

In two years time, Max will be able to do everything in the garage.

We use could or the alternative form was/were able to in simple past.

• We use could for general ability and with the verbs feel, hear, see, smell, taste, remember and understand.
  

  Example:

  Max’s father could do everything in the garage.
  Max’s father could remember changing his first tyre.

• We use was/were able to when we talk about something specific in the past.
  

  Example:

  Was Max able to change the tyre yesterday?

To Note

There is no difference between the negative forms couldn’t and wasn’t/weren’t able to.

Example:

Max’s father couldn’t work in the garage alone.
Max’s father wasn’t able to work in the garage alone.

Should/Ought to for Advice

We use should/ought to to give advice, make suggestions or say what is a good idea.

Example:

Max should/ought to work more often in the garage.

To make suggestions about something that has already happened we use should/ought to + have + past participle.

Example:

Max shouldn’t/ought not to have played computer games all day.

Can/could/may/might for Permission

modal verb	alternative form
can/could/may/might	be allowed to

We use can/could/may/might to ask permission in simple present. Could is more polite than can, and may/might is more polite than could.

Example:

Can/Could/May I leave my car here for repairs?

We usually only use may in questions with I and we.

We only use can or may, but not could, to give permission.

Example:

Max, you can/may change this tyre.

We use could in conditional clauses and in the simple past.

Example:

Max could change the tyre if he wanted to.
Max could/was allowed to leave early yesterday.

We can use be allowed to in all tenses.

Example:

Max will be allowed to use the dangerous equipment soon.

Must/need not/should for Obligation

modal verb	alternative form
must	have to
mustn’t	be not allowed to
need not	don’t have to
should/ought to	be supposed to/be expected to

We use must to say what is necessary and give orders or advice in a strong way. With must, the obligation is usually imposed by the speaker.

Example:

His father says, “You must do what you are told.”

We use have to when the obligation is general (e.g. a rule or law), or we are expressing past or future obligation.

Example:

Max is only 12 so he has to go to school.
Max’s father had to go to school too.

We use mustn’t/be not allowed to to say what is not allowed or forbidden.

Example:

Max mustn’t/isn’t allowed to touch any dangerous equiptment.

We can use should/be expected to like must but it is weaker.

Example:

Max should/is expected to study hard.

We use need not/don’t have to when there is no obligation.

Example:

Max need not/doesn’t have to worry about his future.