His achievements in science are recognized all over the world.

My friend came from Equatorial Guinea.

The calculation of an indefinite integral can be considered as the reverse operation of differentiation.

The calculation of definite integrals is an important part of calculus.

In order to calculate the integral constant, it is necessary to solve the differential equation.

What is the area of this room?

His achievements are very impressive.

He works digging out coal.

I can't forget the impression when I ate kaiseki for the first time.

He is an expert in petrochemistry.