All the auxiliary verbs except be, do and have are called modals. Unlike other auxiliary verbs modals only exist in their helping form; they cannot act alone as the main verb in a sentence.
Be, do, and have also differ from the other auxiliaries in that they can also serve as ordinary verbs in a given sentence.
The modal verbs are:-
CAN / COULD / MAY / MIGHT / MUST / SHALL / SHOULD / OUGHT TO / WILL / WOULD
| Modal | Example | Uses |
| Can | They can control their own budgets. We can’t fix it. Can I smoke here? Can you help me? | Ability / Possibility Inability / Impossibility Asking for permission Request |
| Could | Could I borrow your dictionary? Could you say it again more slowly? We could try to fix it ourselves. I think we could have another Gulf War. He gave up his old job so he could work for us. | Asking for permission. Request Suggestion Future possibility Ability in the past |
| May | May I have another cup of coffee? China may become a major economic power. | Asking for permission Future possibility |
| Might | We'd better phone tomorrow, they might be eating their dinner now. They might give us a 10% discount. | Present possibility Future possibility |
| Must | We must say good-bye now. They mustn’t disrupt the work more than necessary. | Necessity / Obligation Prohibition |
| Ought to | We ought to employ a professional writer. | Saying what’s right or correct |
| Shall (More common in the UK than the US) | Shall I help you with your luggage? Shall we say 2.30 then? Shall I do that or will you? | Offer Suggestion Asking what to do |
| Should | We should sort out this problem at once. I think we should check everything again. Profits should increase next year. | Saying what’s right or correct Recommending action Uncertain prediction |
| Will | I can’t see any taxis so I’ll walk. I'll do that for you if you like. I’ll get back to you first thing on Monday. Profits will increase next year. | Instant decisions Offer Promise Certain prediction |
| Would | Would you mind if I brought a colleague with me? Would you pass the salt please? Would you mind waiting a moment? "Would three o`clock suit you?" - "That’d be fine." Would you like to play golf this Friday? "Would you prefer tea or coffee?" - "I’d like tea please." | Asking for permission Request Request Making arrangements Invitation P |
