导轨安装完工后，检测其不直线度，每5m长应不大于（）mm。
A.1.0
B.1.2
C.1.5
D.1.8
参考答案：B
Echo _____ for half a month. She’ll come hack in two months.
A. left B leave C. has left D. has been away
请回答天枢的主治，叙述并演示血海、天枢的定位及血海的操作。
