He sneaked into the house in the middle of the night.

This book is no longer available anywhere.

He became good at playing the piano, and finally acquired the skill.

He was so ashamed of his failure that he wished he could crawl into a hole.

Due to the earthquake, cracks appeared in the wall.

This information sank in immediately.

His cooking skills are among the top five in the local area.

In this right triangle, since one angle is 30 degrees, its complementary angle is 60 degrees.

The opposite angles of a quadrangle intersect each other.

The wildebeest is a very rare animal.