Modal verbs: meaning and practical use

A modal does not describe the action itself. It tells the listener how to understand that action. Before you choose one, ask whether the person is able to act, allowed to act, advised to act, required to act, or only possibly going to act.

You can wait in the lobby.

Can gives permission in this situation. It does not say that waiting is required.

You must wait in the lobby.

Must makes waiting in the lobby a rule or a strong instruction.

Which modal fits friendly advice about a long journey?

Use should: You should take some water with you. The speaker recommends the action.

After can, could, may, might, must, should, will, and would, use the base form of the main verb. The form stays the same with he, she, and it. Say She can help, not She can helps or She can to help.

Mina should call the clinic this afternoon.

Call is the base form after should, even though Mina is one person.

It might snow on the hills tonight.

Snow follows might in the base form. There is no to before snow.

Choose the correct form: 'He may join us later' or 'He may joins us later'?

Use may join. A modal is followed by the base form join.

Can often shows present ability or permission. Could can describe ability in the past. In a question, could also makes a request sound more polite. The situation tells you whether the sentence is about a skill, permission, or a request.

I can hear the announcement from here.

Can describes the speaker's present ability to hear it.

Could you hold this door for a moment?

Could makes a courteous request. It does not refer to past ability here.

Which request usually sounds more polite: 'Can you wait?' or 'Could you wait?'

Both are natural, but Could you wait? is usually more polite.

Use should when you think something is a good idea. It is useful for recommendations and practical advice. The speaker is guiding the listener, but should does not usually carry the force of a rule.

You should read the instructions before you begin.

The speaker recommends reading first because it may help the listener.

You should not leave your bag near the door.

Should not gives advice against the action. The shorter form is shouldn't.

Complete the advice: 'If your screen is hard to read, you ____ increase the text size.'

Use should. Increasing the text size is a recommendation.

Must gives a strong instruction, rule, or sense of necessity. In a negative sentence, must not means that an action is prohibited. This differs from do not have to, which means that the action is optional.

Passengers must show a ticket before boarding.

Showing a ticket is a requirement for passengers.

You must not block the fire exit.

Blocking the exit is forbidden.

Which phrase means that bringing a pen is optional?

Use do not have to bring a pen. Must not bring a pen would mean that bringing one is forbidden.

May and might show that something is possible, not certain. In many everyday sentences, might sounds more cautious. May can also be used for formal permission, as in You may begin when you are ready.

We might take the earlier train if the meeting ends soon.

Taking the earlier train is possible, but the speaker has not decided.

You may leave your coat at reception.

May gives formal permission to leave the coat there.

Which modal fits an uncertain weather forecast: 'It ____ rain this evening'?

Use might or may. Both show that rain is possible rather than certain.