轴承的功用有二，一为支承轴及轴上零件，并保持轴的旋转精度，二为减少转轴与支承之间的（）。
参考答案：摩擦和磨损
—Last night Ted was late for the party again.
—You know, ______.[ ]
A. a good beginning is half done
B. Honesty is the best policy
C. a leopard can not change its spots
D. a work ill done must be twice done
除氧器主要作用是除去水中（）。
A.氧气
B.杂质
C.微生物
D.钙镁离子
