He is immersed in the study of panmagic squares.

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

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

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

He is the type of person who thinks it's a moonlit night if it's bright, so he only has a one-sided perspective.

He thought deeply and said, 'I think, therefore I am.'

He is a perfectionist, so he is very strict about his work.

He played a perfect fifth scale on the piano.

He strongly believes in the philosophical thought, 'I think, therefore I am.'

He said, 'Where there is a will, there is a way,' and faced the difficult situation.