Essential English Modal Verbs: Functions and Examples
Understanding the Core Functions of English Modal Verbs
Modal verbs modify the main verb to express ability, possibility, permission, obligation, or advice. Below is a detailed breakdown of their primary uses and corresponding examples.
CAN: Ability, Permission, and Impossibility
- Ability: I can speak English. / He can find any street in London.
- Permission (Informal Request): Can I go to the toilet?
- Suggestion: You can take a taxi.
- Request: Can you take me to Victoria Station?
- Probability (0% / Certain Impossibility): It can’t be Susan. She is in Paris. / That story can’t be true.
COULD: Past Ability, Probability, and Polite Requests
- Past Ability: She could speak Chinese when she was 5 years old. / I could play tennis when I was younger.
- Past Permission: She could go to the cinema.
- Probability (Approx. 30%): It could get much colder in January.
- Polite Request: Could I go to the toilet? / Could you take me to Victoria Station?
- Offer or Suggestion: I could lend you my dictionary. / You could take a taxi.
MAY: Probability and Formal Permission
- Probability (Approx. 50%): It may rain tomorrow. / It may be quicker to travel by train.
- Permission (Formal): May I go to the cinema with you? / May I come in?
MIGHT: Low Probability
- Probability (30% or less): It might snow today. / It might be quicker to travel by train.
MUST: Deduction and Obligation
- Prohibition: You mustn’t play with that. It’s dangerous.
- Deduction / Certainty (100%): The visitor must be Daniel. I’ve seen his car outside. / Look at the snow. It must be cold outside.
- Obligation (Strong Internal): You must be back at 10 o’clock.
SHOULD and OUGHT TO: Advice and Opinion
- Advice / Opinion (SHOULD): You shouldn’t smoke. It’s bad for your health. / You should drive more carefully.
- Advice / Opinion (OUGHT TO): You ought to drive more carefully.
WILL: Prediction and Spontaneous Decisions
- Prediction: I think he will study harder this time.
- Spontaneous Decision: Oh, it’s very cold in here. I’ll close the window.
Additional Semi-Modal Verbs and Related Uses
BE ABLE TO (Ability)
- He is able to find any street in London.
HAVE TO (Obligation)
- You have to be back at 10 o’clock.
NEED TO (Obligation / Necessity)
- Do you need to study a lot?
Prohibition and Lack of Obligation
- MUSTN’T (Prohibition): You mustn’t drive without a license.
- NEEDN’T (Lack of Obligation): You needn’t have a university degree.
- DON’T HAVE TO (Lack of Obligation): You don’t have to call a taxi.