When most dinosaurs disappeared eighty million years ago, some kinds of animal survived. 当大多数恐龙在8000万年前灭绝时，一些动物幸存了下来。

　　Crocodiles were one of them. 鳄鱼是其中之一。

　　People believe that crocodiles were living two hundred million years ago. 人们相信鳄鱼自两亿年前就存在了。

　　Crocodiles have very thick and green skin. 鳄鱼有厚厚的绿皮。

　　Some kinds of crocodiles like to live in fresh water and others like salty water. 有些种类的鳄鱼喜欢生活在淡水中，有些则喜欢咸水。

　　They usually eat fish, reptiles and mammals. 它们通常吃鱼类、爬行类和哺乳类动物。

　　If you ever saw a crocodile, you might think they look very slow. 如果你曾经见过鳄鱼，你可能会觉得它们行动缓慢。

　　As a matter of fact, they are very fast. 事实上，它们行动迅速。

　　Also, they have very strong teeth and jaws. 而且，它们的牙齿和下巴非常强壮。

　　These characteristics make crocodiles one of the most dangerous animals in the world. 这些特征使鳄鱼成为世界上最危险的动物之一。