He is a person who does not forgive evil.

He hates bad food.

Don't stick your head out.

I didn't think he would come.

He is passionate about researching pure mathematics.

He is majoring in applied mathematics at university.

He is a world-famous mathematician.

Combinatorics is a branch of mathematics that studies combinations of things.

Combinatorics is a branch of mathematics that studies combinations of things.

Combinatorics is a branch of mathematics dealing with issues of order and choice.