In our country, the system of popular representation forms the basis of democracy.

He was chosen to represent us at the conference.

I am very interested in natural science.

He is an expert in physical anthropology, conducting research on human evolution.

He is an expert in fluid mechanics.

I see dogs in the park every day.

His behavior is really disgraceful.

The troposphere is the lowest part of the Earth's atmosphere, and most of the weather occurs here.

My son has started learning taekwondo.

He has full authority over this project.