My eyes hurt.

He regards me as a friend.

Her eyes are beautiful.

He saw snow for the first time.

He always thinks the grass is greener on the other side.

Her eyelids are getting heavy, maybe she is tired.

He likes to take a walk in the park at dusk.

Cytogenetics is a science that studies the structure and function of chromosomes and genes.

This allele greatly affects the inheritance of color vision.

He is known as an expert in population genetics.