单项选择题
A.inside the bearing
B.outside the bearing
C.covering the crankshaft
D.none of the above
单项选择题 The machine has stopped rotating because the bearing （） the shaft.
单项选择题 The lubricating system for the cylinder walls is different from the bearings in that the oil for former one is supplied in （） while that for latter one is （）.
单项选择题 The lubricating pipes and dusts should be blown out with （）.