万能外圆磨床的内圆磨具,其主轴两端采用滚动轴承,并依靠()的推力,使轴承实现预紧,消除了轴承中的(),从而保证了主轴有较高的回转精度和刚度。
参考答案:弹簧;原始游隙
Jim is always going to sleep with his bedroom light ______.[ ]
A.on
B.with
C.in
D.by
炉水内加磷酸三钠,其药品的含量不得小于()
A、92%
B、30%
C、58%