阅读理解。
Do you know all birds protect themselves by always listening and watching out for er? At the
smallest sign of it, they will fly away. Birds that cannot fly are often able to swim fast, or run quickly.
Some birds make themselves look bigger and more erous by fluffing (抖动) their feathers.
Another important protection for many birds is their colors. Their feathers often have colors that match
the things around their nests (巢). Some birds change colors with the seasons. In the winter they are white
to match the snow. In the summer they are brown to match the ground.
People sometimes kill birds without meaning to. When people cut down forests to build houses and
factories, they destroy the homes and food of birds. If the birds have nowhere else to go and nothing to eat,
they will die out.
Pollution may cause some birds to die. Birds that eat fish from polluted water get poison in their bodies.
Then they cannot lay healthy eggs. New birds can't be born.
Now people protect birds passing the laws to control hunting and pollution, by setting up some special
parks where all the birds are safe from hunters, and by teaching people to care about birds rather than kill
them.
How do birds protect themselves?By 1______.
By fluffing their feathers.
By having colors that match the things around their nests.
By changing 2______.
Why do some birds die out?People sometimes kill birds without meaning to.
3______. may cause some birds to die.
4______? By passing the laws to control hunting and pollution.
By setting up 5______.
By teaching people to care about birds.