The Mesolithic is the era between the Paleolithic and the Neolithic.

He was deeply grieving the death of his family.

Infrared astronomy provides a new perspective on understanding the universe.

I stabbed the needle for the injection.

The Riemann sum is a method for approximately calculating the integral of a function.

His performance is generally good.

He followed the footprints left on the snow.

He was appointed as the chief executive officer of the company.

His hair is thin and long.

He was feeling loneliness.