精密偏心套夹具设计中，定位圆弧中心线与车床回转中心的距离公差是工件偏心距公差的（）。
A.1/3
B.1/4
C.1/5
D.1/6
参考答案：A
Floors aboard ship are（）.
A.frames to which the tank top and bottom shell are fastened on a double bottomed ship
B.transverse members of the ships frame which support the decks
C.longitudinal beams in the extreme bottom of a ship from which the ships ribs start
D.longitudinal angle bars fastened to a surface for strength
厕所马桶的冲洗使用什么动力？（）
A.气源
B.电马达
C.抽真空
