He is teaching mathematics to the students.

Oil is an important element of the world economy.

She played the piano with her fingertips.

This lamp used to light up with whale oil in the past.

I sent you an email.

The sending of the email has been completed.

He went through great hardship to complete the project.

He experienced great hardship to complete the project.

Please look at my new camera.

He was known as a divine troop.