按加油机泵源可分为（）加油机与潜油泵加油机。
A、叶片泵
B、齿轮泵
C、离心泵
D、自吸泵
参考答案：D
You needn't_ for him. [ ]
A. to wait
B. waiting
C. wait
D. to waiting
立圆弧的半封闭直角槽，应选用（）铣削加工。
