Reading his biography, you can understand how difficult his life was.

A positron is a particle that carries the opposite charge of an electron.

My landline phone broke down recently.

The greater the electric potential difference, the faster the current flows.

I have been to Yuntian.

We conducted an experiment on electrolysis in chemistry class.

The chemist electrolyzed water to produce hydrogen and oxygen.

He was surprised to receive an unexpected phone call.

He suddenly made an unexpected phone call to my house.

The old gathering place was crowded with people.