Animals United is a 3D German cartoon which is directed by Reinhard Klooss and Holger Tappe. It is a story about animals that get together to find water. Along their journey, lots of funny things happen, and of course, they have a lot of adventures.

    The animals in the grasslands in Africa are waiting for the coming flood. However, this year's flood seems to come later than in other years. The animals become upset and worried. At the same time, some animals from other places come to the grasslands to look for peace. However, the situation seems worse because the water is becoming less and less. So they decide to look for the river.

    Finally, they find the reason why they don't have any water to drink. A dam(坝) has been set up so that humans can have a better life. After a long fight with humans, they let the world know that animals are in danger.

    This film is about environmental matters. The humans are the bad and the animals are the good. This film is to give humans a warning that they must not destroy the homes of animals or damage nature in order to improve their own life. Humans should know that animals also have their own world.

根据短文内容，选择正确答案。

增加：在缺词处加一个漏词符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1). 每处错误及其修改均仅限一词；

2). 只允许修改10处，多者（从第11处起）不计分。

    I asked Jack, a friend of mine, what has happened to him that night. He said that he had just got into bed on about half past eleven when the floor began to shake under him. The bed was also started shaking. He jumped out of his bed rapid and wanted to turn the light on. But the floor was shaking such violently that he could hardly reach the lamp. It seemed to take him long time to get to it and turned it on. Then he went to look out of the window. He saw that the houses on the other side of the street was also shaking. Then he knew that was happening — an earthquake! He quickly put on his clothes and ran out into the street to waiting until it was safe to go back inside.

如图所示，铁桶重为20N，桶的底面积为100cm²，往桶里倒入8kg的水，水的深度为15cm，平放在面积为1m²的水平台面上（g取10N/kg）．求：