1.1 Which of the following statements are true? For the false statements, explain why you think they are false: (a) Feedforward and feedback control require a measured variable. (b) For feedforward control, the measured variable is the vari- able to be controlled. (c) Feedback control theoretically can provide perfect control (i.e., no deviations from set point) if the process model used to design the control system is perfect. (d) Feedback control takes corrective action for all types of process disturbances, both known and unknown. (e) Feedback control is superior to feedforward control.