The flags of all nations are fluttering in the wind.

Flags of all nations are displayed in this park.

He is studying old literature.

This secret medicine is the secret to longevity.

His research brought about a significant leap forward in science.

His business made a big leap forward this year.

She takes contraceptive medicine every day.

In his study of international law, he particularly focuses on jus gentium.

I am studying Japanese.

Seeing his pitiful figure, tears came to my eyes.