There is a planned blackout tonight, so please come home early.

He is systematically advancing his work.

I work at a travel agency.

I looked in the telephone directory and searched for his number.

That traveller is travelling around the world.

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

Please remember to bring your travel documents.

The students on a field trip visited the museum.

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

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