This figure is symmetric.

He is good at algebra.

This equation is linear.

This is a linear mathematical problem.

There was a long queue in front of the movie theater.

People were forming a line from early morning to buy concert tickets.

He received the letter challenging him to a duel and began preparing for the duel.

Gender roles are an important element in defining individual behavior in society.

His role is to fulfill his responsibilities as a leader.

It is important to understand the importance of health.