He is a Chinese person.

He ate one apple.

I reserved a single room.

My grandfather is being seen by a specialist in geriatric medicine.

An old person was playing with his grandchild in the park.

An old person was walking in the park.

He is known as an expert in gerontology.

My grandfather is interested in gerontology.

My grandmother lives in a nursing home.

My grandmother participates in the local old people's club every week.