单项选择题
A.more sealing water is needed
B.the cover clamp needs tightening
C.the purifier has a bad vibration when started
D.water is discharged from the overflow line
单项选择题 If fuel oil were being discharged from the waster outlet of a fuel oil disk type centrifuge, operated as separator, you should（）
单项选择题 One engine manufacturer recommends heavy fuel oil should not be heated above 80℃ to 95℃ (176 ℉ TO 203℉) before purificationThis upper limit should be observed to ensure against（）
单项选择题 Which of the substances listed is satisfactorily removed from the fuel by a centrifugal oil purifier?（）