Most birds live in places where it is light during the day. They can use their eyes to see where they are going. The oilbirds of South America live in dark caves. They use their ears to help them find their way.
The oilbird is a brown bird with owl-like eyes. It nests on a high ledge in an ink-black cave. It only leaves the cave at night to hunt for food and returns before dawn.
The oilbird flies in circles in its dark cave. There is not enough light for it to see clearly with its large eyes. As the oilbird flies, it uses its voice to make sharp, clicking sounds. These clicks bounce off the cave walls and become echoes.
The oilbird listens to the echoes it has made. If the echoes take a long time to come back, the bird knows it is far from the wall. If they return quickly, the bird is close to it. In this way, the oilbird hears how far it is from the wall.
Oilbirds spend their lives in the dark, yet they never bump into the walls of their cave homes. We say that oilbirds “see” with their ears.
1. Oilbirds live _________.
A. on mountain tops B. in dark caves
C. on the ground D. in nests in trees
2. The story does not say so, but it makes you think that _________.
A. oilbirds do not like light B. oilbirds are blind
C. most birds sing only in the dark
3. Oilbirds leave their caves at night to _________.
A. exercise B. play
C. hunt for food D. see their friends
4. On the whole, this story is about _________.
A. echoes that are heard in caves
B. owls that live in the dark
C. the oilbirds of South America
5. How do the clicking sounds help an oilbird inside a cave?
A. They are signals to other birds.
B. They become echoes that help it find its way.
C. They mean the bird is getting ready to eat.
参考答案：1. B 2. A 3. C 4. C 5. B
