Start here. Read slowly — this is the key that opens everything else.
A modal verb is a little helper word we put before a main verb to change its meaning — not the action, but our attitude toward it. They tell the listener how sure, how polite, or how necessary something is.
✔ She should call him. ✘ She should to call / should calls / should calling.
Think of the four modals as a scale — from a soft suggestion to a strong obligation:
← weaker / more optional stronger / more obligatory →
Each box = one modal. Read the uses, then the examples in colour.
could
- Something is possible (not certain)
- A gentle suggestion (one option)
- A polite request for help
- Past ability: "I could swim at age 10."
You could try the new café.
Could you help me, please?
may
- Something is possible — like could, a bit more formal
- Asking/giving permission politely
- Common in writing, signs, polite speech
May I ask a question?
You may leave when you finish.
should
- Giving advice — "this is a good idea"
- What is correct or expected
- shouldn't = advice against
We should book early.
You shouldn't drive when tired.
must
- Something is necessary / obligatory
- A strong, personal "no choice" feeling
- must not = it is prohibited
I must finish this tonight.
You must not smoke here. (forbidden!)
These are the differences students mix up most. Compare them side by side.
Both mean "it's possible." May sounds a little more formal and is the usual choice for asking permission. In everyday speech, could is more relaxed.
"It could snow." = "It may snow." · "May I come in?" feels more correct in formal settings.
Should = it's a good idea (you can still say no).
Must = there is no real choice (an obligation or a rule).
"You should see a doctor." → advice. · "You must wear a seatbelt." → it's the law.
A famous trap! They are opposites:
| Phrase | Meaning | Example |
|---|---|---|
| must not | It is forbidden — don't do it! | You must not park here. |
| don't have to | It's optional — your choice | You don't have to come early. |
Warm-up on the golden rule. After a modal, which verb form is correct?
Tap the modal that fits the meaning. You'll get feedback right away.
Read the short story, then mark each sentence True or False.
Sofía uses her phone about 6 hours every day. Last week her doctor said, "You should not use your phone so much. It may affect your sleep. You must give your brain time to rest." Her friend Elena said, "You could put your phone in another room when you sleep. May I show you an app that tracks your screen time?" Sofía decided to try. She must not use her phone after 10 PM. After two weeks, she sleeps much better. She thinks, "I should have done this a long time ago."
Tap a beginning on the left, then its correct ending on the right.
Beginnings
Endings
Type one modal in each blank, then press Check. The word bank can help.
Paula is moving into her first apartment alone next Saturday. She has a long list of things she do before she moves in. First, she call the landlord today — the heating is broken. She also buy some basic things: a bed, towels, and plates. Her friend offers to help. " you help me move the boxes on Saturday?" Paula asks. "Of course!" her friend says. "But you forget to rent a van — the boxes are too heavy for the car. The weather be bad on Saturday too, so we check the forecast first. And you drive if you haven't slept!" Paula smiles. Moving is hard, but she is ready.
The big trap. Choose must not (it's forbidden) or don't have to (it's optional).
Each sentence has ONE modal mistake. Read it, think of the fix, then reveal the answer.
Read the meaning, then choose the rewrite with the correct modal. This tests if you really feel the difference.
Use the ▲ ▼ arrows to reorder the lines into a logical story, then check.
A mixed review: meaning, base form, negatives, and the tricky pairs — all in one.