Through this chemical reaction, monomers polymerize to form polymers.

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

Doublet is an important concept in linguistics.

He is fifty years old and still full of energy.

The thirteenth day of the month is my birthday.

He was playing video games all day.

Our project is scheduled to be completed on the twentieth day of the month.

My younger sister is seventeen years old.

My birthday is on the twenty-eighth.

My grandfather is seventy years old.