When the counting time of PMT is 10 seconds, the ratio between the concentration of NO (PPB) and the counting rate (CPS) is 1:5.是什么意思_When the counting time of PMT is 10 seconds, the ratio between the concentration of NO (PPB) and the counting rate (CPS) is 1:5.在线翻译_英语_读音_用法_例句