润滑油过滤器压差如果大于正常值，则应（）。
A.切换和清洗润滑油过滤器
B.提高润滑油温度
C.降低润滑油温度
D.开大润滑油泵出口阀门
参考答案：A
This dictionary is _____ to me, but that one is _____ . [ ]
A. great help; helpful
B. a great help; of little use
C. important; of few importance
D. very helpful; of no any use
