单项选择题
A.open loop control
B.feedback
C.combining control
D.integral process
单项选择题 The gauge pressure inside a container is -0~5kg/cm2, then what is the absolute pressure exerted to the inside surface of thin container?（）
单项选择题 The crane jib is raised and lowered by means of （）
单项选择题 Which one of three elements for a fire on a tanker vessel is most difficult to eliminate (isolate)?（）