He is in the middle of studying for the exam.

Cultural exchange between China and Korea is very important.

Mr. Nakai is my best friend.

By regularly checking the key performance indicators, you can understand the performance of the company and devise improvement measures.

The pronghorn, native to North America, is characterized by its speed and beautiful horns.

He is doing a special exercise to train his scalene muscles.

Amphibole, a type of mineral, is mainly found in igneous rocks.

The horned puffin lives in the cold waters of the North Pacific.

The spiny dogfish is a type of fish that lives in the deep sea.

A diagonal matrix is a matrix in which all elements outside the main diagonal are zero.