He returned the sword to its sheath.

Her behavior seemed mysterious.

His father was diagnosed with schizophrenia in the past.

The impact of the unequal treaty is still deeply rooted in our society.

Ri is wearing black clothes.

He is traveling around the world in search of the elixir of life.

He is an expert in primatology and is engaged in the study of gorilla behavior.

This old radio uses a cold-cathode tube.

I have been to Salt Lake City.

A cooling device utilizing the principle of radiative cooling has been developed.