自动控制系统中的开环控制系统有两种，一种是按设定值进行控制，另一种是按（）大小进行控制。

A、被控变量

B、操纵变量

C、干扰量

D、设定量

_____ three times in a row, the boxer decided to give up fighting. [ ]

A. Having defeated

B. To have defeated

C. Having been defeated

D. To have been defeated