单项选择题
The mode of control employed by an alarm circuit is a （）
A.two position control B.signal speed floating control C.proportional speed floating control D.reset control
单项选择题 The meat box temperature control circuit, as used in ship service refrigeration system, is an example of （）
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 （）
