One day, a poor man was travelling on horseback. At noon, he tied his 1 to a tree and then sat down to eat something.
A few minutes later, a rich man came along and tied his horse to the 2 tree. “Please 3your horse to another tree,” said the poor man.” My horse is wild. It will kill 4” But the rich man said, “I shall tie my horse as I like!” He tied up his horse and had his lunch nearby.
After a moment they heard a terrible noise, the two horse were 5. They went up to them, but it was too late. The rich man's horse was killed. “See what your horse has done!” cried the rich man. “You will have to6it.” And he brought the poor man before the judge(法官).
The judge asked the poor man some questions. But he made no 7. At last the judge said, “This man is dumb(哑的). He cannot speak.” “Oh.” the rich man shouted 8, “He can! He spoke to me when I met him.” “Are you sure?” asked the judge. “What did he say?”
“He told me not to tie my horse to the same tree 9his horse was wild and would kill my horse.” “Oh.” said the judge. “So he warned you. And can you expect to get money from him?” The rich man said 10 and left silently.
机械能守恒的是：