This mineral is called ulexite and has special optical properties.

He is an expert in analytical mechanics and deeply understands its theory.

The Paleolithic is the first era of human history.

His service record is very excellent.

My brother is a famous biologist.

I use a tram for commuting every day.

It is rumored that he is a member of a secret society.

The continental slope is a part of the seafloor topography, connecting the continental shelf and the deep sea floor.

He is a world-renowned ichthyologist.

The SI system is a standard unit system used worldwide.