The Nile is the longest river in Africa.

Mr. Koiwai is my best friend.

The Thames is one of the most famous rivers in the UK.

The Tigris is one of the important rivers in Asia.

This area is affected by multiple contamination.

Groundwater pollution has become a serious environmental problem.

We should recycle to prevent environmental pollution.

He started deducing the case.

Madagascar is a country rich in nature.

The long meeting ended, and I am hungry.