His promise was empty words.

In this radiation therapy, we use röntgen to destroy cancer cells.

I am planning to go to Gangwon next week.

He denied his previous remarks.

A determiner plays a role in specifying a noun.

What is the amplitude of this sine wave?

The sine, which is one of the trigonometric functions, represents the ratio of the radius of a circle to the opposite side of a right triangle.

Collagen is an important component for keeping our skin and bones strong.

This grave atmosphere reminds us of how important a place we are in.

This solemn atmosphere reminds us of how important a task we are undertaking.