在距滚子轴端面25mm处测量，直径磨耗大于（）时更换。
A.1mm
B.2mm
C.3mm
D.4mm
参考答案：C
I’m very pleased with the results of my blood test, for all tested items show _____ reactions.
A．negative
B．good
C．positive
D．correct
观测期间越长越好。
