单项选择题
A.Correct the cause of the scoring and repair the sleeve or replace with a new one
B.Reassemble the unit and provide more water leak off for proper lubrication
C.Check for parallel alignment of the sleeve radial faces to the sleeve bores
D.Reassemble the unit and adjust the governor to obtain a slower speed
单项选择题 Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?（）
单项选择题 For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes?（）
单项选择题 The flame safeguard control system of a large automatic auxiliary boiler will provide fuel shut off in the case of high （）.