Here are some characteristics of modal verbs:
- They never change their form. You can't add "s", "ed", "ing"...
- They are always followed by an infinitive without "to" (e.i. the bare infinitive.)
- They are used to indicate modality allow speakers to express certainty, possibility, willingness, obligation, necessity, ability.
Use of modal verbs:
Modal verbs are used to express functions such as:Here is a list of modals with examples:
- Permission
- Ability
- Obligation
- Prohibition
- Lack of necessity
- Advice
- possibility
- probability
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 |