岗位是系统根据工作需要划定的具有一个人满负荷工作量的工作单元，是职务和职责的统一体。它有三个基本属性：工作性、（）和层次性。
参考答案：专业性
水力发电厂有几种类型？各有什么特点？
Parents of a child with cystic fibrosis demonstrate knowledge of the effects of hot weather on their child when they state that hot weather is hazardous because the child has which of the following（）
A. Poor ability to concentrate urine.
B. Little skin pigment to prevent sunburn.
C. Poorly functioning temperature control center.
D. Abnormally high salt loss through perspiration.
