Circadian rhythms regulate our sleep-wake cycle.

I need to order some printed circuit boards for the project.

The circular functions are used to describe the relationship between the angles of a circle and the lengths of its sides.

Short circuit operators are used in programming languages.

Short-circuit operators are used in programming languages to evaluate expressions efficiently.

The blue circles rates are increasing.

He tries to square the circle.

He attempted to square the circle, but it proved to be impossible.

When asked if he wanted dessert, John replied, 'Circle gets the square!'

She loves wearing circle skirts.