单项选择题
A.2100N/s±200N/s B.2200N/s±100N/s C.2400N/s±100N/s D.2400N/s±200N/s
A.0.75% B.1.15% C.1.25% D.1.50%
A.15%~40% B.20%~40% C.20%~50% D.30%~50%