The river flows through the city.

City, country, river are categories in a word game.

The hippopotamus is swimming in the water.

Hippos are strong and fascinating animals.

The river flows calmly and steadily downstream.

The river flows quickly upstream.

Flow control is important for data transmission.

Perch are colorful fish.

The European perch is a freshwater fish that occurs in many European waters.

The teeth of the hippopotamus are impressive.