The children were playing tag in the park.

He really is a music child, isn't he?

He was observing the movement of the pendulum.

An imaginary number, or 'kyosu', is not a real number, but refers to a number whose square root is a negative number.

He recognizes the danger of extremism.

He calls himself a communist.

Please be careful when crossing the road.

I am moving to Kitamoto next week.

This timber is rated as having good lumber grade.

Mr. Kiguchi is my best friend.