I learned how to calculate definite integrals in math class.

The calculus of variations is a branch of mathematics that deals with the optimization of functions.

In this company, being late is not allowed as an unwritten rule.

He wrote a poem using the four treasures of the study.

The cultural festival will be held at our school next week.

He has a deep interest in the European cultural sphere.

He is my sworn elder brother, always protecting me.

My pet Java sparrow is very cute.

He analyzed the light of the stars using a new spectroscope.

I think that information is just hearsay.