Modals
Modals (modal auxiliaries) are helping verbs that express the speaker's attitude — ability, permission, possibility, obligation, advice, willingness or habit. The principal modals are can, could, may, might, will, would, shall, should, must, ought to, need, dare, used to.
Key Features of Modals
- Modals never change form — no -s, -ing or -ed is added. (He can swim, never He cans swim.)
- A modal is always followed by the base form (V1) of the verb: She must go, not She must goes/going.
- Modals form questions and negatives without do: Can he come? He cannot come.
- Modals have no infinitive form — we say to be able to, not to can.
Functions of the Main Modals
| Modal | Function | Example |
|---|---|---|
| can | ability; informal permission | She can speak three languages. / Can I borrow your pen? |
| could | past ability; polite request; possibility | He could run fast as a boy. / Could you help me? |
| may | formal permission; possibility; wish | May I come in, sir? / It may rain today. / May you live long! |
| might | remote possibility; very polite request | He might join us later. |
| will | future; willingness; determination | I will help you, don't worry. |
| would | past habit; polite request; preference | Grandfather would tell us stories. / I would rather walk. |
| shall | suggestion/offer (with I/we); formal future | Shall we begin? |
| should | advice; moral duty; expectation | You should revise daily. |
| must | compulsion; strong necessity; logical certainty | You must wear a helmet. / He must be tired after the journey. |
| ought to | moral obligation; desirability | We ought to respect our elders. |
| need (needn't) | absence of necessity | You needn't wait for me. |
| dare | courage (mostly negatives/questions) | How dare you touch my files? |
| used to | discontinued past habit/state | She used to live in Patna. |
Choosing Between Close Pairs
can vs may
Can shows ability or informal permission; may is the formal, polite choice for permission and also shows possibility. In a classroom or office context, prefer May I…?
must vs should
Must expresses compulsion or an order (no choice); should gives advice (a choice remains). Passengers must carry ID (rule) vs You should sleep early (advice).
would vs used to
Both show past habits, but only used to can describe a past state: There used to be a well here (not would be).
may vs might
Might signals a weaker, more remote possibility than may, and is the past form of may in reported speech.
Modals in Reported Speech
| Direct | Reported |
|---|---|
| can | could |
| may | might |
| will / shall | would / should |
| must | had to (compulsion) |
| could, would, should, might, ought to | no change |
Common Errors
| Wrong | Right | Reason |
|---|---|---|
| He can swims well. | He can swim well. | Modal + base form only. |
| She must to finish the work. | She must finish the work. | No to after must. |
| We ought help the poor. | We ought to help the poor. | Ought always takes to. |
| He did not dare to said a word. | He dared not say a word. | Modal dare takes bare V1. |
| I use to play cricket. | I used to play cricket. | Fixed form is used to. |
| You don't need wait. | You needn't wait. | Modal need + bare infinitive. |