词汇训练：.用适当的词填空（共10小题，每题1分，满分10分）
As everyone knows, the skin is 小题1: （必不可少的）to us. Our skins can sometimes小题2: (burn) due to our 小题3: (粗心). Therefore, first aid shows its importance in the小题4:（治疗） of burns. Generally speaking, burns, 小题5: are caused by hot liquids, fire, radiation and so on, can be divided into three types－first degree, second degree and third degree 小题6: (depend) on the 小题7: (受伤的) layers of the skin. To minor burns, cool water proves to be helpful in 小题8:（stop）the burning process and preventing or reducing pains. But 小题9: severe burns, get the 小题10: to the doctor immediately.
