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

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

This system is very complex.

The government declared a state of emergency to prevent the spread of the new coronavirus.

Paleoecology is a field of study that investigates the relationship between past organisms and their environment.

He is an expert in paleoecology, pouring his passion into studying past ecosystems.

I have been to Wuhai city.

The White Sea is a sea located in the northern part of Russia.

Mr. Kaiboku is my best friend.

The common murre lives in the oceans of the Northern Hemisphere.