1. CAN - COULD - MUST SHOULD - HAVE TO - MAY - MIGHT
MODAL VERBS
CAN COULD MUST
SHOULD HAVE TO MAY MIGHT

2. CAN We use can: a) to express ability: I can swim
b) to express possibility or permission:
They can find some berries in the forest
Yes, you can stay if you want

3. COULD We use could : to express ability or possibility in the past:
I could run really fast when I was young
b) in the interrogative form it can also be used to ask for permission:
Could you pass me the salt, please?

4. MUST and HAVE TO
-We use must to talk about obligation. When we use must the authority comes from the speaker: You must eat all your vegetables -We also use “have to” to talk about obligation. However, in this case authority usually comes from external circumstances: We have to wear a safety belt

5. SHOULD We use should to give advice or to suggest something:
You shouldn’t eat all the cake, you’ll get sick
We should book that flight to Venice

6. MAY AND MIGHT We use may and might to express probability.
If we use might we express less certainty.
-We may see some parrots when we visit the rainforest
-They might be tired when they arrive