Modals (also called modal verbs, modal auxiliary verbs, modal auxiliaries) are special verbs which behave irregularly in English. They are different from normal verbs like "work, play, visit..." They are used to indicate modality. They give additional information about the function of the main verb that follows it. They have a great variety of communicative functions.
Modal verbs are used to express functions such as:
- Lack of necessity
Modal verbs are followed by an infinitive without "to"
- You must stop when the traffic lights turn red
- You should see to the doctor
- There are a lot of tomatoes in the fridge. You need not buy any.
- You ought to go to the doctor
Here is a list of modals:
|to have to||100 % obligation||I must stop when the traffic lights turn red.|
|to be very probable||logical conclusion (deduction)||He must be very tired after such enormous work|
|not to be allowed to||prohibition||You must not smoke in the hospital.|
|to be able to||ability||I can swim|
|to be allowed to||permission||Can I use your phone please?|
|it is possible||possibility||Smoking can cause cancer !|
|to be able to||ability in the past||When I was younger I could stay up all night and not get tired..|
|to be allowed to||more polite permission||Excuse me, could I just say something?|
|it is possible||possibility||It could rain tomorrow!|
|to be allowed to||permission||May I use your phone please?|
|it is possible, probable||possibility, probability||It may rain tomorrow!|
|to be allowed to||more polite permission||Might I use your phone please?|
|it is possible, probable||weak possibility, probability||I might come and visit you in America next year, if I can save enough money.
|necessary||necessity||Need I say more?|
|not necessary||lack of necessity/absence of obligation||I need not buy any tomatoes. There are plenty in the fridge.|
|used to say or ask what is the correct or best thing to do||50 % obligation||I should / ought to see a doctor. I have a terrible headache.|
|to suggest an action or to show that it is necessary||advice||You should / ought to revise your lessons|
|to be very probable||logical conclusion (deduction)||He should / ought to be very tired after such enormous work|
|to suggest an action or to show that it is necessary||advice||You 'd better revise your lessons|