1. Certainty:
My boss will be in his office at 9 am.
He's sure to give us an important assignment.
My mum is certain that my brother is smoking.
2. Probability:
This girl will probably win the race tomorrow.
Perhaps she will invite us for a pizza.
You probably won't find the answer on the Internet.
3. Possibility:
It might snow tomorrow.
It's possible that my uncle won't visit me after all.
She may call you if you give her your number.