Show:
Ability
Obligation
Necessity/Insistence
Possibility
Permission/Requests
100
Five years ago, I (cannot, couldn't) play the piano.
Five years ago, I couldn't play the piano.
100
When I grow up, I (may, might) become an engineer.
When I grow up, I may become an engineer.
100
I think I (will, would) go to the beach this Sunday.
I think I will go to the beach this Sunday.
100
We have enough milk in the fridge so we (must, mustn't, needn't) buy some more.
We have enough milk in the fridge so we needn't buy some more.
100

May I come in?

(allow)

Yes, you  may.

200
We (can, could) speak English well.
We can speak English well.
200
(Might, May) I have a glass of water?
May I have a glass of water?
200
I am feeling tired. I think I (would, will) go to sleep now.
I am feeling tired. I think I will go to sleep now.
200
Time is not on our side. We (must, mustn't, needn't) hurry.
Time is not on our side. We must hurry.
200

May I take your phone? (reject)

No, don't.

300
The volleyball team (can, could) go to the Olympics this year if they are lucky.
The volleyball team could go to the Olympics this year if they are lucky.
300
There is a small chance that we (may, might) go to the beach this weekend.
There is a small chance that we might go to the beach this weekend.
300
I (will, would) try to act like my father when I was young.
I would try to act like my father when I was young.
300
Mary gave me a letter to send. I (must, mustn't, needn't) forget to mail it.
Mary gave me a letter to send. I mustn't forget to mail it.
300

May I go to the cinema? (ban)

No, you mustn't. 

400
I (cannot, couldn't) run that fast when I was six years old.
I couldn't run that fast when I was six years old.
400
If you leave the stove on, the house (may, might) catch on fire.
If you leave the stove on, the house might catch on fire.
400
If you get in trouble, I (won't wouldn't) help you.
If you get in trouble, I won't help you.
400
You (must, mustn't, needn't) wash those carrots. They've already been washed.
You needn't wash those carrots. They've already been washed.
400

....I leave ? 

can, may

500
I think I (can, could) help you learn math if you study hard.
I think I can help you learn math if you study hard.
500
Billy and I (may, might) cook dinner tonight.
Billy and I may cook dinner tonight.
500
(Will, Would) you like steak or chicken?
Would you like steak or chicken?
500
He will be having lessons for another two hours. We (must, mustn't, needn't) visit him now.
He will be having lessons for another two hours. We mustn't visit him now.