单项选择题
Diesel engine main and connecting rod precision bearings are made in halvesEach half exceeds one-half the bearing circumference by a small amountThe small amount is termed （）.
A.clearance B.crush C.pitch D.thrust
单项选择题 If an operating auxiliary boiler has a water pH reading of 7, you should （）.
单项选择题 Generating tubes in waste heat boilers are finned to （）.
单项选择题 Directional intake ports in diesel engines are used to （）.
