I have been to Chicago.

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

Linear programming is a part of operations research and is used to find the optimal solution.

Paying the urban planning tax is a citizen's duty.

The United Nations Environment Programme is providing solutions to global environmental problems.

He thoroughly researched the history of that nation.

He is a famous composer.

He is a famous lyricist who has produced many hit songs.

He is a very excellent performer.

He dreams of becoming a famous cartoonist.