It is important for each person to fulfill their role.

That person is my friend.

I went to see a movie by myself.

Watching a movie alone is enjoyable.

This recipe requires a certain amount of ingredients.

He makes it a point to read a certain number of books every month.

The budget for this project is set and will not change.

In this equation, x is a variable and 5 is a constant.

That woman is my mother.

That man is my father.