单项选择题
A.two position control
B.signal speed floating control
C.proportional control
D.reset control
单项选择题 The two most common gases used in pneumatic system are （）
单项选择题 Restrictions occurring in the small orifices of pneumatic control system components can be used by （）
单项选择题 In a pneumatic automation system, a unit producing a signal to govern the position of the controller of the measured variable, relative to the value of the measured variable, is said to have（）.