Due to the earthquake, the city declared a state of emergency.

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.

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

His character has the power to seckill enemies.

He seckilled the enemy in the game.

This light bulb consumes one watt-second of energy per second.

He thought for a few seconds before giving an answer.