Modals

auxiliaries verbs.

When are modal verbs used? 

Modal verbs are used to express functions such as:

Advice

  • You should / ought to revise your lessons

Ability

  • She can speak six languages.
  • My grandfather could play golf very well.
  • can’t drive.

Command

  • You must wash your hands before cooking.
  • You need to be here before 8:00.

Habits

  • When I lived in Italy, we would often eat in the restaurant next to my flat.
  • John will always be late!

Lack of necessity

  • I need not buy tomatoes. There are plenty of tomatoes in the fridge.

Likelihood

  • Her parents must be so proud.
  • My baby brother should be asleep by now.

Obligation

  • Children must do their homework.
  • We have to wear a uniform at work.
  • You should stop smoking.

Permission

  • Could I leave early today, please?
  • You may not use the car tonight.
  • Can we swim in the lake?

Prohibition

  • You must not smoke in the hospital.

Possibility/Probability

  • It may rain tomorrow!
MODAL VERB EXPRESSING EXAMPLE
must Strong obligation You must stop when the traffic lights turn red.
logical conclusion / Certainty He must be very tired. He’s been working all day long.
must not prohibition You must not smoke in the hospital.
can ability I can swim.
permission Can I use your phone, please?
possibility Smoking can cause cancer.
could ability in the past When I was younger I could run fast.
polite permission Excuse me, could I just say something?
possibility It could rain tomorrow!
may permission May I use your phone, please?
possibility, probability It may rain tomorrow!
might polite permission Might I suggest an idea?
possibility, probability I might go on holiday to Australia next year.
need not lack of necessity/absence of obligation I need not buy tomatoes. There are plenty of tomatoes in the fridge.
should/ought to 50 % obligation I should / ought to see a doctor. I have a terrible headache.
advice You should / ought to revise your lessons
logical conclusion He should / ought to be very tired. He’s been working all day long.
had better advice You’d better revise your lessons