Modal verbs - přednáška

COULD/MIGHT – for possibilities depending on certain conditions

I could/might go with you if I can get a day off.

CAN’T/COULDN’T – used for things we know are impossible or to make negative deductions

This can’t be what she wanted because the colour is different.

MAY NOT/MIGHT NOT – something is possibly not the case

Why is Jana absent. – She may not know about the meeting.

CAN/COULD/MIGHT (less certain) + NOT + perfect infinitive – negative deduction about the past

The man you met yesterday can’t have been my brother. He is on holiday.

MAY cannot be used in a question, can, could or might have to be used instead. Can/could might it be true?

(refers only to “possibility, deduction…”, not e.g. “permission”)

PERMISSION

CAN/MAY (more formal), COULD + MIGHT (more tentative)

past: COULD/COULD NOT – general permission

In the past we could not travel in Western Europe.

NOT ALLOWED TO – specific permission

I was not allowed the keep the puppy I found in the park.

OBLIGATION

MUST X HAVE TO/NEED TO - obligation imposed by the speaker X obligation imposed by authority other than the speaker or outer circumstances

past + future: for both must and have to we use had to - I had to go to the doctor yesterday. I will have to soon decide what to do after the graduation.

SHOULD/OUGHT TO - often less strong alternative to MUST since their meaning is also subjective

BE TO/OBLIGED TO/ SUPPOSED TO/ REQUIRED TO – objective, based on authority

All visitors are to/are required to/ are supposed to report with the reception.

PROHIBITION AND CRITICISM

Present + future: MUSTN’T, CAN’T, MAY NOT, NOT ALLOWED TO, SHOULD NOT/OUGHT NOT TO

Past: COULDN’T, SHOULD NOT/OUGHT NOT + perfect infinitive; WAS/WERE NOT ALLOWED TO

ABSENCE OF OBLIGATION

Present: (objective) DON’T HAVE TO, DON’T NEED TO, NEEDN’T (subjective)

Children uder six don’t have to/don’t need to pay for public transport. You need’t/don’t need to hurry. Pavel is not here yet.

Past: DIDN’T HAVE TO/DIDN’T NEED TO – we don’t know if the action happened or not, it more likely didn’t

I didn’t have to take an entrance exam thanks to my good results at secondary school.

NEEDN’T HAVE DONE – the action happened, but it was not necessary

We got up really early to catch the first train, but at the station we realised that it goes only on Sundays – we needn’t have got up so early.

LOGICAL DEDUCTION AND PROBABILITY

Present + future: MUST, SHOULD (NOT)

You must still remember her, you went to school together.

If we catch the train at 7 o’clock we should reach our destination before noon.

Past: MUST + perfect infinitive

You must have seen the film. It has been on TV more than 5 times.

Negative: CAN’T

This can’t be the place – there’s nobody inside and there are no lights on.

CAN’T/COULDN’T + perfect infinitive

The man you met could not have been my brother because he is on holiday.

SHOULD is not normally used to predict negative or unpleasant situations