The protection of this town is my responsibility.

The feline immunodeficiency virus can potentially have serious effects on a cat's health.

My cat has been infected with the feline immunodeficiency virus.

The human immunodeficiency virus destroys the immune system, causing the body to lose its ability to fight disease.

The human immunodeficiency virus is the virus that causes AIDS.

He was out of breath after running a long distance.

Alkynes play an important role in organic chemistry.

Alkenes play an important role in organic chemistry.

Alkenes play an important role in organic chemistry.

Alkanes are basic components of organic chemistry.