If you're hungry, try eating some belly.

My room is the quietest in the house.

I like the character in the middle.

In math class, I learned about the concept of intersection.

In math class, the teacher explained the concept of relative complement.

In math class, we learned about the concept of union.

The concept of the absolute complement plays an important role in set theory.

Set operation is one of the basic concepts in mathematics.

He is learning how to use collective nouns.

In mathematics, an empty set refers to a set that does not contain any elements.