We use this coordinate system to locate the position of an object.

We are a part of the Milky Way.

He found her on a dating website.

The ecosystem of this lake is very fragile.

In physics, the inertial frame of reference is a very important concept.

This system is very complex.

He is deeply involved in the study of the meridian system.

Because her immune system is weak, she catches a cold easily.

He loves visual kei bands.

He is interested in radio wave research.