【单选题】While inspecting the main bearings on a diesel engine you find impregnated dirt and scratches in the bearing surface .you would, therefore, suspect that _______.
A.
the bearing had been overheated
B.
water was present in the oil
C.
the lube oil was not being properly filtered
D.
the maximum allowable bearing pressure had been exceeded
【简答题】根据短文内容,从短文后的七个选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。 Why Cats Scratch Things It has long been assumed that when cats scratch objects with their front paws (爪子) that they are sharpening their paws. 1_____ Resea...