一台水泵每秒钟内可把76.5kg水扬高10m,带动水泵的电动机的输入功率为12kW,电动机的效率是85%,g=10N/kg,则水泵的效率是____。
The policeman often helps the old woman walk _____________ the bridge.
This is Mr White's ________ trip to Beijing. He has been there twice before.