Liquid oxygen is often used as rocket fuel.

He is traveling around the world as an ecologist.

We must strive to protect the natural environment.

We should recycle to prevent environmental pollution.

We need to solve the problem in the production environment.

It took a long time to set up the development environment.

His nature is very kind.

Detailed information is needed to understand the nature of that project.

I was moved by his sincerity.

His nature is very kind.