The birds began to sing at the break of dawn.

There is an old cellar in my house.

Eurasia geographically includes Europe and Asia.

Southern crabgrass is growing in my garden.

He started an education program to solve the problem of illiteracy.

He is dedicated to the study of immunochemistry.

Thermochemistry is a part of chemistry that deals with the reactions of heat and matter.

This chemical reaction is very dangerous.

This shirt is made of chemical fiber.

The use of chemical weapons is prohibited by international law.