He is always hanging out with bad friends. Truly, birds of a feather flock together.

I have been to Chicago.

The Paleogene period was a very important time in the history of the Earth.

I have been to Outer Mongolia.

I am planning to go to Inner Mongolia, an autonomous region of China, next week.

The American continent is where diverse cultures and nature coexist.

The whooping crane is an endangered species, and it is difficult to see its beautiful figure.

The American red wolf is one of the endangered species.

My dream is to live in the United States of America someday.

He likes to take a walk in the park at dusk.