Topology is a branch of mathematics that abstracts and generalizes the concept of space.

My grandfather is sixty-six years old.

He is acting like catching a thief and tying him up by pointing out others' mistakes without admitting his own failures.

He is studying the shape of a tetrahemihexahedron.

Fluoromethane plays an important role in chemical reactions.

Chloromethane is often used in organic chemistry experiments.

Difluoromethane is widely used as a refrigerant.

In this chemical reaction, cyclohexane is the main product.

Cyclopentane is a compound often used in organic chemistry.

Cyclooctane plays an important role in organic chemistry.