A positive-definite matrix is an important concept in linear algebra.

She is conducting research on the world's oldest profession.

He publicly acknowledged that he is a transsexual.

The World Trade Organization is an important organization that sets the rules for international trade.

The World Health Organization is working to improve public health worldwide.

It is important to respect the rights of intersexual people.

He is a Chinese person.

He urged us to hurry, saying 'time and tide wait for no man.'

He is a foreigner, but he can speak Japanese fluently.

Please imagine the day when aliens come to Earth.