bet-weenBNC²³⁶²¹³⁺¹ 例句 An experiment was done for the free vibration frequency of a single span and simple supported liquid pipe, resulting in the relationship bet-ween the free vibration frequency and the flow velocity. 实验对单跨简支输液管道的自由振动频率进行了测试,得到了自由振动频率随流速变化的关系。 chemyq