例句與造句

1. It is indicated that , when a two - speed motor is used for driving oil transfer pump , the motor with the characteristic of torque reduction on square rotary speed should be chosen ; the working economy of the variable speed pump is restricted by the characteristic curves of pipeline resistance , and its speed control range is restricted by the pipeline resistance characteristic curve , the pressure head needed by the system and the working characteristic of the pump ; when several pumps work in parallel , the pump with better performance should be changed into speed - variable pump
   指出雙速電動機用于輸油泵的調速時，應選用轉矩按轉速平方降低特性的電動機；調速泵的運行經濟性受到管路阻力特性曲線的限制，其調速范圍受到管路阻力特性曲線、系統(tǒng)所需揚程和泵運行特性的限制；在母管制系統(tǒng)中把部分定速泵改為調速泵時，應將性能較高的定速泵改為調速泵。
2. It's difficult to find speed-variable pump in a sentence. 用speed-variable pump造句挺難的