Burns are common injuries in our daily life. People can get    小题1:  by a variety of things, such as hot oil, steam, fire and so on. There are   小题2: types of burns—first degree, second degree or third degree, depending on which layers of the    小题3: are burned. If the burns, especially the third type, are not properly    小题4: , they may lead to serious problems. So knowledge of first aid is vitally   小题5:  .

"富营养化"现象说的是水质污染。