He raised his hand.

I'm spending the happiest days imaginable.

I am spending the happiest days of all.

There is a New Year's celebration in January.

He always likes to be the first to comment on videos.

The tip of this pen is only 1 millimeter.

In this experiment, we will use the International System of Units.

An imaginary unit is an important concept in mathematics.

An astronomical unit represents the average distance from the Earth to the Sun.

This product has a very small assembly unit.