单项选择题
A.变频调速 B.被力耦合器调速 C.变频调速和被力耦合器调速 D.晶闸管串级调速
A.10%~20% B.30%~60% C.40%~50% D.50%~70%
A.25% B.70% C.50% D.85%
A.60%~70% B.20%~30% C.30%~40% D.10%~30%
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