单项选择题
When reassembling the bowl of a disk-type centrifuge, the bowl or locking ring is rotated （）.
A.clockwise, due to the bowl rotating clockwise B.clockwise, due to the bowl rotating counterclockwise C.counterclockwise, due to the bowl rotating clockwise D.counterclockwise, due to the bowl rotating counterclockwise
单项选择题 In diesel engines designed with a crosshead, the motion of the piston rod can be described as （）.
单项选择题 Immediately after any diesel engine is started, the engineer should check the （）
单项选择题 The rate of heat transfer in a water-tube auxiliary boiler can be increased by （）.
