单项选择题
A.500N/s±50N/s B.1000N/s±100N/s C.2400N/s±200N/s D.2500N/s±250N/s
A.5%~10% B.5%~15% C.6%~10% D.6%~15%
A.C3S B.C2S C.C3A D.C4AF