2. CAN/CANT'T
● Ability:
I can speak English.
● Possibility:
We can take a train at 5.
● Permission:
You can use a dictionary.
● Ability:
I can't speak Chinese.
● Possibility:
We can't take a train. It's late.
● Deduction:
This pen can't be mine. Mine is blue.
4. MUST/MUSTN'T
● Internal Obligation:
I must visit my friend.
● External Obligation:
I must stop the car at the red light.
● Deduction:
She is very nice. She must have a lot of friends.
● Prohibition:
You mustn't smoke here.
● No obligation/need:
We don't have to wear a uniform