Genki is my best friend.

Mr. Kumamoto is my best friend.

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

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.

The exam ended and the results were good, so I thought 'all's well that ends well'.

The piston of the engine is moving.

Kozue is my best friend.

Mozi's thoughts had a great influence on ancient Chinese philosophy.