The musk deer is often used as a source of fragrance.

In chemistry class, I learned about the process of polymerization.

Through this chemical reaction, monomers polymerize to form polymers.

My room is twenty-five square meters.

During the war, he continued to support his family on the home front.

He is fifty years old and still full of energy.

Doublet is an important concept in linguistics.

My birthday is on the fifteenth.

He was working throughout the entire night.

My younger sister is twenty-two years old.