A.instigating corrective actionB.indicating values of c……

单项选择题A feedback is an input（）

A.which governs the state of a variable
B.which provides a visual and audible alarm
C.which indicates values of controlled variables
D.which measures the state of the controlled variable

单项选择题The closed-loop system differs from the open-loop system by（）

A.the lack of a feedback
B.the presence of a feed back
C.the lack of a computer
D.the presence of a computer

单项选择题From the passage, we can learn that the simplest controller action is（）

A.two-step controller action
B.proportional, controller action
C.integral controller action
D.derivative controller action

单项选择题Which kind of the following controllers is the most sophisticated controller?（）

A.Proportional controller
B.Integral controller
C.Derivative controller
D.PID controller

单项选择题The word “offset” most probably means（）

A.predetermined value
B.measured value
C.off-limit
D.sustained deviation