MINI-GRAMMAR LESSON: Modals of obligation, permission & prohibition (present & past time)

Modals of obligation, permission and prohibition (present & past time)

Permission

We use can + infinitive and is/are allowed to + infinitive to talk about permission in the present.

You can vote in Morocco when you are eighteen.
The children are allowed to watch TV until ten o'clock.

We use could + infinitive and was / were allowed to + infinitive to talk about permission in the past.

Many years ago people could smoke anywhere.
He was allowed to stay out until twelve o'clock.

Obligation

We use must + infinitive and has / have to to talk about obligation in the present.

You must arrive 30 minutes before your flight.
We have to leave soon.

We use had to + infinitive to talk about obligation in the past.

He had to pay a lot of tax last year.

No obligation / Lack of obligation

We use needn’t+ infinitive , don't /doesn't have to + infinitive and don't / doesn't need to + infinitive talk about something that is not necessary (but it is allowed).

You don't have to come if you don't want to.
I don't need to wear a tie to work.

We use didn't have to + infinitive and didn't need to + infinitive to talk about an absence of obligation in the past.

We knew the restaurant manager so we didn't have to pay for our meal.
They didn't need to get up early because it was a holiday.

Prohibition

We use can't + infinitive, mustn't + infinitive and isn't / aren't allowed to + infinitive to talk about something that is not allowed, something which is forbidden.

You can't enter Spain without a visa.
You mustn't open your papers before the exam begins.
The students aren’t 't allowed to take mobile phones to school.


We use couldn't + infinitive and wasn't/weren't allowed to + infinitive to talk about prohibition in the past.

Moroccan school children couldn't have long hair in the 1960s and 1970s.
The children were not allowed to speak.