An isotope refers to elements with the same atomic number but different numbers of neutrons.

Transition elements play an important role in chemical reactions.

Oxygen, which is one of the chemical elements, is necessary for us to breathe.

The process of terraforming is part of transforming other planets into a habitable environment for humans.

Earth science is an important field of study for unraveling the mysteries of nature.

I am an Earthling.

We are searching for extraterrestrial life.

In learning Japanese grammar, understanding the upper two-step conjugation is important.

It takes twenty minutes to get to my house.

There is a test in two days.