An identity matrix is a square matrix in which all the elements on the diagonal are 1 and all other elements are 0.

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.

The air in this area is greatly affected by pollutants emitted from factories.

The existence of dark matter has not yet been fully proven.

Antibiotics don't work for colds, so please don't take them unnecessarily.

It is said that antimatter has properties opposite to those of matter.

We exist as a part of the material world.

This food may contain carcinogens.