Police dogs are very effective in tracking criminals.

He was terrified of living in a police state.

The head of the police station explained the details of the incident to the press.

He was caught by the secret police.

A municipal police was established in my town.

How does this machine work?

Please underline this word.

We go fishing in this river every weekend.

Every weekend, we enjoy picnics on the flood plain along the river.

The use of fossil fuels is causing global warming.