题目内容：

    Did you ever see a fish with its very own lights? Some fish have built-in lights. That is, the lights are really part of the fish’s body! One such fish lives in the Red Sea. It is called the “flashlight fish” because it has special body parts, or organs, that give off light.

The flashlight fish has one light organ underneath (在下面）each eye. These lights are bright and greenish in color, and they are always “on”. But a flashlight fish can hide its lights by raising an extra (额外的）piece of skin up over each organ. Then, when the fish lowers the skin,the lights can be seen again.

What are these special lights for? The light organs help the fish find food at night along the Red Sea reefs (暗礁).They also help the fish run away. Usually,the lights are flashed “on” and “off’ about once every 20 seconds. But when the fish is worried, it will blink (眨眼）its lights about 75 times in 1 minute. Can you imagine 20 or 30 flashlight fish blinking their lights all at the same time?

1.In the passage,the underlined word “organ” means _____.

A.an extra piece of skin B.a special body part

C.a kind of eye D.a kind of ear

2.The flashlight fish uses its lights to hunt for food and to      .

A.change color B.hide its eyes

C.run away from danger D.catch other fish

3.When a flashlight fish is worried, its lights will         .

A.flash more slowly B.flash faster

C.turn bright green D.blink many times

4.How often are the lights usually flashed?

A.Three times a minute. B.Twice a minute.

C.About 75 times a minute. D.Once a minute.