Every year in Australia there are crocodile (鳄鱼) attacks (攻击) on humans. Two years ago, a 24-year-old German tourist died when she went ____ in a lake. Although there were signs warning people that there might be crocodiles, the girl and ____ friends decided to have a midnight swim. The girl ____ disappeared and the next morning her body was found. Near it was a four-meter crocodile. And only last month two____ boys watched in fear as their friend was killed by a crocodile. They were washing their mountain bikes in a river at that time. Then, those two boys climbed a tree and stayed there for 22 ____while the crocodile waited below.