This phenomenon remains unexplained for scientists.

With daily practice, his skills are definitely leveling up.

I am aiming to level up my Japanese by practicing every day.

His Japanese ability is high-level.

His explanation was impossible to understand.

His work is full of vigour.

There is a possibility that unknown lifeforms exist on this planet.

The study of artificial life is a new frontier in science.

What is the molecular formula of this compound?

He is conducting research on natural phenomena.