潜油电机是潜油电泵机组的（），它驱动潜油离心泵吸取地下的原油。
A.发动机
B.发电机
C.动力机
D.电源
参考答案：C
Mr Brown was________chairman of the budgeting committee, which was a surprise to everyone
even including himself.[ ]
A. labeled
B. nominated
C. assigned
D. appointed
简述SSPD的工作过程。为什么要以电荷存储方式工作？
