Mario was on the plane back to Xinjiang. He read a story.
Long long ago, there 1 two birds, one was Tom Bird and 2 was Bob Bird.
One day, they3 in the forest. Tom Bird said he could fly much 4 than Bob Bird. But Bob Bird didn't believe, he thought he could fly higher than any birds. Tom Bird 5 in the sky, he saw many 6 , he had a good idea. He said: "I'll fill(装满) my bag7 salt(盐), and you put some cotton(棉花) in your bag, let's have a match, who can fly higher with a bag?"
Bob Bird smiled, he thought, salt is much heavier than cotton, so he would win.
The two birds 8 up into the sky with the bags in their backs. Suddenly(突然) it began to 9 .
At last, 10 Bird flew higher, and became a winner.
Dear friends, do you know why?
