We use the solar calendar.

We calculate time using the solar calendar.

The use of this machine is simple.

This computer can be used by anyone.

The ocean covers most of the surface of the earth.

The durability of this washing machine is 10 years.

A solar day is the time it takes for the Earth to orbit around the Sun.

He explained the gist of the story.

I strive for body care by doing moderate exercise and eating a balanced diet every day.

I couldn't understand the state of his behavior.