6.蝙蝠和雷达

Lesson Six

Bats and Radar

1.There are two bright spots in the clear night sky, which are getting closer and closer.It can be seen clearly that there are two lights, one red and one green.

2.Then came the rumbling sound.It was a plane flying at night.

3.How can an airplane fly safely in the dark night?

4.It turned out that people got inspiration from bats.

5.Bats fly at night and can catch moths and mosquitoes; no matter how they fly, you have never seen they collide with anything.Even a very thin wire can be deftly avoided.

6.Is its eyes so sharp that it can see everything clearly in the dark night?

7.In order to make it clear, scientists made an experiment more than one hundred years ago.

8.In a room, a lot of ropes were strewn at random, and many bells were tied on the ropes.

9.They blindfolded the bat and let it fly in the house.

10.The bat flew for hours, but none of the bells rang.It didn’t touch any of the ropes.

11.Scientists have done two more experiments: one is to plug the bat’s ears, the other is to seal the bat’s mouth and let it fly in the house.

12.Bats bump around without destination, making the bells ring on the ropes.

13.Three different experiments have proved that bats fly at night not by their eyes, but by their mouths and ears.

14.After repeated studies, scientists finally uncovered the secret that bats can fly at night.

15.As it flies, it makes a sound from its mouth.

16.This kind of sound is called ultrasonic, which can’t be heard by humans, but can be heard by bats.

17.Ultrasonic waves move forward like waves, and are reflected back to the ears of bats when the waves falls across barriers, and the bats immediately change the direction of flight.

18.Scientists imitated bat’s way of exploring the road and installed radar on the plane.

19.The radar sends out radio waves through the antenna, and the radio waves are reflected back and displayed on the screen when they encounter obstacles.

20.From the radar screen, the pilot can clearly see whether there are obstacles ahead, so it is safer for the plane to fly.