Ability
Five years ago, I (can't, couldn't) play the piano.
Ability
Five years ago, I couldn't play the piano.
When I grow up, I (must, might) become an engineer.
Possibility
When I grow up, I might become an engineer.
I think I (should, would) like to go to the beach this Sunday.
Intention
I think I would like to go to the beach this Sunday.
We have enough milk in the fridge so we (mustn't, don't have to) buy more.
Obligation
We have enough milk in the fridge so we don't have to buy more.
(May, must) we stay up till midnight?
Permission
May we stay up till midnight?
We (can, could) speak English well.
Ability
We can speak English well.
(Might, May) I have a glass of water?
Possibility
May I have a glass of water?
I am feeling tired. I think I (would, should) go to sleep now.
Advice
I am feeling tired. I think I should go to sleep now.
Time is not on our side. We (have to, should) hurry up.
Obligation
Time is not on our side. We have to hurry up.
(Can, may) I go to the bathroom?
Permission
May I go to the bathroom?
The volleyball team (can, could) have gone to the Olympics last year if they had been lucky.
Ability
The volleyball team could have gone to the Olympics last year if they had been lucky.
We (may, should) go to the beach this weekend.
Possibility
We may, go to the beach this weekend.
I (should, would) try to act like my father when I was young.
Intention
I would try to act like my father when I was young.
Mary gave me a letter to send. I (mustn't, don't have to) forget to mail it.
Obligation
Mary gave me a letter to send. I mustn't forget to mail it.
No, you (can't, couldn't) go to that party.
Permission
No, you can't go to that party.
I (can't, couldn't) run that fast when I was six years old.
Ability
I couldn't run that fast when I was six years old.
If you leave the stove on, the house (could, would) catch fire.
Possibility
If you leave the stove on, the house could catch fire.
If you got in trouble, I (wouldn't, can't) help you.
Opinion
If you got in trouble, I wouldn't help you.
You (must, don't have to) wash those carrots. They've already been washed.
Obligation
You don't have to wash those carrots. They've already been washed.
(Would, can) you give me a glass of water, please?
Request
Would you give me a glass of water, please?
I (can, could) help you study for the math exam.
Ability
I can help you study for the math exam.
Billy and I (may, couldn't) cook dinner tonight.
Possibility
Billy and I may cook dinner tonight.
You (should, could) eat more vegetables.
Advice
You should eat more vegetables.
It's my cousin's birthday. I (have to, mustn't) call him.
Obligation
It's my cousin's birthday. I have to call him.
My brother says I (may, might) use his computer.
Permission
My brother says I may use his computer.