standard plain milling cutter

例句：

1. 1. The standard for measuring the length ofa ruler is 20 cm.
   测量尺的标准长度是20厘米。
2. 2. Thecompany has adopted a standard operating procedure toensure quality.
   该公司已采用标准操作程序以确保质量。
3. 3. The standard deviation measures how spreadout the data points are from the mean.
   标准差衡量数据点与均值的距离。