I don't know if he will come.

Understanding the principle of electromagnetic induction is very important in learning physics.

Freedom of the press is one of the fundamental elements of democracy.

He is learning how to use gerunds.

He continued hard labour all day long.

I perform work every day.

His behavior is flexible like an adjectival noun.

This machine is driven by electricity.

This earthquake caused a large motional disturbance.

He was emotionally disturbed when he heard the news.