_______control system is one in which the control action is independent of the output.
A.Feed back
B.Negative feed back
C.Close loop
D.Open loop

A.降低货币数量
B.降低银行支票存款
C.增加银行准备金
D.增加银行资产
E.增加银行法定准备金

A.预制桩
B.灌注桩
C.摩擦桩
D.端承桩

A.ultra
B.universal
C.unit
D.unattended