He is researching about a new energy source.

He is conducting research on a new energy source.

This lake is very deep.

His eyes were filled with deep sorrow.

The Sumatran tiger is one of the endangered species.

The Siberian tiger lives in the forested areas of Siberia.

The Siberian tiger is an incredibly powerful animal, and its strength and speed are astonishing.

I love ox tongue.

His split tongue is the reason he looks like a snake.

I used pentane in a chemistry experiment.