单项选择题
A.to be kept
B.logged
C.changed
D.has remained
单项选择题 The oil was pumped up in the settle tank such a height that it ().
单项选择题 The oil quantity for bearing lubrication should be applied in such an amount as to be sufficient to carry away the () caused by the friction at the bearings.
单项选择题 The oil lubricating diesel engine cylinders usually contain additives formulated to impart a high degree of alkalinity to () the acid conditions.