This thermometer uses mercury.

The economy of this region has been greatly revitalized due to the development of water transportation.

His level of Japanese is very high.

Hydrogen is the most abundant element in the universe.

He talked about the horror of the hydrogen bomb.

He found a leaf floating on the surface of the water.

The seawater of this beach is very clean.

This dam generates electricity using waterpower.

The underground water in this area is very clean and delicious.

This river is polluted with contaminated water.