（）齿轮泵和柱塞泵是液压泵常见的三种结构形式。
参考答案：叶片泵
采用电子计算机系统代替手工记账的单位，要有严格的操作管理制度。( )
The new policy will _____ the elders a lot that people over 65% can take buses free of charge. [ ]
A. discount
B. support
C. approve
D. benefit
