He was looking proud when he heard that his son had been accepted to college.

He is proud of his son's success.

This 'Ra' shirt is very light.

Believing that failure is a stepping stone to success, he challenged again.

Believing that failure leads to success, he continued to challenge himself over and over again.

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.

He is a person of strong vanity who reads self-improvement books.