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

My cat has been infected with the feline immunodeficiency virus.

His Japanese ability is improving gradually.

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.

I heard the sound of cicadas in the park.

Demography is an important tool for understanding various aspects of society.

His efforts were like a mantis trying to stop a chariot, he couldn't achieve any results.

He is the champion of the stone, paper, scissors game.

The single transferable vote is an important means to ensure the fairness of elections.