cavity frequency meter

例句：

1. 1.The cavity frequency meter is used to measure the frequency of sound waves in a cavity.
   腔室频率计用于测量声波在腔室中的频率。
2. 2. The cavity frequency meter was used to detect the presence of gases in the air.
   腔室频率计被用来检测空气中的气体存在。
3. 3.The cavity frequency meter was used to measure the frequency of sound waves in a cavity.
   腔室频率计被用来测量声波在腔室中的频率。