DSC-5000型双筒试井车钢丝绞车滚筒最大提升负荷为（）kN。
A、5
B、5.5
C、6
D、6.5
参考答案：B
The doctor ____ is leaving for Africa next month.
A．the nurse is talking to him
B．whom the nurse is talking
C．the nurse is talking to
D．who the nurse is talking
火星大冲每（）年发生一次
A、19-21
B、13-15
C、17-19
D、15-17
