按给定值与实际值比较后的差值进行控制叫做（）
A.开环控制
B.复合控制
C.正反馈控制
D.闭环控制
参考答案：D
With the new technique ______, the factory produced ______ family cars in 2009 as the year before.[ ]
A. to introduce; three times many as
B. introduced; three times as many
C. introducing; three times as many
D. being introduced; three times many as
婚姻的成立
