使用数控铣床应定时检查（）。
A、润滑油油位
B、机床坐标系位置
C、电机
D、数控系统
参考答案：A
A 70-year-old client with a diagnosis of left-sided cerebrovaseular accident is admitted to the facility. To prevent the development of disuse osteoporosis, which of the following objectives is most appropriate
A．Maintaining protein levels.
B．Maintaining vitamin levels.
C．Promoting weight-bearing exercises.
D．Promoting range-of-motion (ROM) exercises.
什么是工质的熵？其在动力工程上有何作用？
