操作设备应具有明显的标志，包括：命名、编号、（）、旋转方向（）的指示、及设备相色等。
参考答案：分合指示；切换位置
---Why are you still here? It's so late.
---Because I my work. Don't worry. It's almost done.
A．wasn't finishing
B．wouldn't finish
C．haven't finished
D．won't finish
在单相流体的换热中，按照流体流动的原因可以分为自然对流换热、强迫对流换热和（）三类。
