单项选择题
A.boiler water level is low
B.feedwater is too hot
C.boiler steam demand is low
D.feedwater is too cold
单项选择题 Fuel is admitted to a diesel engine cylinder through the （）.
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 （）.
单项选择题 If an operating auxiliary boiler has a water pH reading of 7, you should （）.