Every child likes listening to stories. Zoe, a girl with wings, is no exception. Listen carefully and see what story her father is going to tell her.

"Now, Zoe, stop fluttering around, and I will tell you a story."
"A true story, papa?"
"It all happened exactly as I'm going to tell you. Two thousand and eleven years ago in 1985, a tribe of beings from the Dog Star invaded Earth. They were called An-vils."
"And what did these beings look like, father?"
"Like humans in many, many respects. They each had two arms, two legs, and all the other organs that humans are endowed with. But they also had a pair of wings and long, purple tails."
"How many of these beings were there?"
"Exactly three million and forty-one male adults and three female adults. In five weeks' time these creatures were the masters of the entire globe."
"Didn't the Earthlings fight back?"
"The humans warred against the invaders, using bullets, ordinary bombs, super-atom bombs and gases."
"What were those things like, father?"
"Oh, they passed out of existence long ago. The humans fought each other with such things."
"And not with ideas, like we do now?"
"No, with guns, just as I told you. But the weapons couldn't harm the invaders. Then the humans tried bacteria against the Star beings."
"What were those things?"
"Tiny bugs that the humans tried to inject into the bodies of the invaders to make them sicken and die. But the bugs had no effect at all on the An-vils. You must know, these newcomers were more intelligent than the Earthlings. In fact, they were the greatest mathematicians in the Milky Way."
"Then, father, the invaders killed off all the Earthlings?"
"Not all. They killed many, but many others were enslaved."
"Then everything was peaceful on Earth?"
"For a little while. Then, some of the most daring of the humans, led by a man named Knowall, escaped into the interior of Greenland. This Knowall was a psychiatrist and he figured out a way to rid the earth of the An-vils."
"How, papa?"
"He filled these An-vils with human emotions, such as love, hate, ambition, jealousy, envy, despair, hope, fear, shame and so on. Very soon terrible civil wars wiped out two-thirds of the An-vil population."
"Then the An-vils finally killed off each other?"
"Almost, until among them a being named Zalibar preached the brotherhood of all An-vils. The invaders quickly quit their quarrels, and the Earthlings were even more enslaved."
"Oh, papa, weren't Knowall and his followers awfully sad about it?"
"For a while. Then Knowall came up with the final way. He filled the An-vils with homesickness."
"Oh, wasn't Knowall smart? That meant, the An-vils were all filled with the desire to fly back to the Star from where they had started."
"Exactly. So, one day, at a given signal, all the An-vils rose up from Earth."
"So then all the An-vils flew away from Earth?"
"Not all. There were two child An-vils, one male and one female, aged two years, who had been born on Earth. They flew up too, but when they reached the upper limits of the atmosphere, they hesitated, turned tail and fluttered back to Earth. Their names were Zizzo and Zizza."
"And what happened to Zizzo and Zizza, papa?"
"Well, they were also great mathematicians. So, they multiplied."
"Oh, papa," laughed Zoe, flapping her wings excitedly, "that was a very nice story!"

Listen to the recording two or three times and then think over the following questions:

1. How did the Earthlings fight against the invasion of the An-vils? Were they successful?
2. What was Knowall by profession ? What tricks did he use to drive away the invaders? Was he successful?
3. How come all the An-vils rose up from Earth at a given signal one day and flew back to their own star?
4. Can you guess what the texts of this unit are going to be about?

The following words in the recording may be new to you:

flutter v. 振翼，拍翅
endow vt. 賦予
Earthling n. 地球人
bacteria n. 細(xì)菌
enslave vt. 使成為奴隸，奴役