c20抗压强度如下:21.0,21.8,23.9,21.1,21.4,21.7.c25抗压强度如下:25.8,25.9,25.5,25.9c25抗压强度如下:28.0,28.7,26.4(本人不是干试验的,但需要计算抗压强度标准差,不会,请高人帮忙!!!谢谢!!!)