A mosquito net is necessary for summer nights.

The public prosecutor's office is investigating the incident.

In ancient times, small countries used to send tributes to the great powers.

Every year, they paid tribute to the king.

His intonation indicated that he was angry.

How long is the perimeter of this rectangle?

He was chosen as the leader of our class.

He went to see a movie with his Korean friend.

I looked in the telephone directory and searched for his number.

The penguin lives in Antarctica.