Tokyo is one of the prefectures in Japan.

His room is unclean, and needs to be cleaned.

Canes Venatici is a spring constellation, and although it is small, it contains several bright stars.

This invention brought about an epoch-making advancement in science and technology.

He lost everything.

She is planning a date with her current boyfriend.

My boyfriend gave me a gift.

Everyone was surprised by the news.

"Once in a lifetime" means to cherish the encounter that happens only once in one's lifetime.

He missed a once-in-a-lifetime opportunity.