科一科二 · 科一
Ducks Don't Get Wet
Ducks are water birds. All day long they go in and out of the water. In and out, in and out.
No matter how many times they go into the water, ducks don't get wet. Ducks are waterproof.
Every duck is waterproof because it has an oil gland nearits tail. With its broad bill, the duck strokes this oil gland. Thenit smears the oil over its feathers. This is called preening.
Ducks spend hours preening themselves. That is how they keep their feathers coveredwith oil. Their feathers do not get wet because oiland water do not mix. Water rolls right offthe oily feathers.
Ducks spend most of their time in the water. They splash around in puddles and ponds, in swampsand shallow streams.
