G92 X（U）-Z（W）-I-F-加工圆锥螺纹时，当X向切削起始点坐标小于切削终点坐标时I为（）。
A.负
B.正
C.零
D.不确定
参考答案：A
The soldier drank a little water and continued_________ that old lady on his back. [ ]
A. carry
B. carrying
C. to carry
D. carries
