I woke up at the witching hour.

Following the customs of the time, they celebrated the festival.

During rush hour, the trains are very crowded.

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.

I'm sorry, but I don't speak Japanese.

I'm a Muslim, so I fast during Ramadan.

I'm Jewish.

She used to be a prostitute, but now she has started a new life.