按流量大小，液压泵有（）之分。
A.定量泵
B.变量泵
C.高压泵
D.低压泵
E.中压泵
参考答案：A, B
—What fruit is in season now?
—Grapes and peaches， ______.
A．I know
B．I think
C．I see
D．I feel
子组织理论方法揭示了什么？
