ppm ['pi:p'i:'em]

例句:

• The term parts per million ( ppm ) was widely used but frequently led to misinterpretation.
  广泛使用百分之几 ( ppm ) 表示结果,但常常引起误解.
  
• Note: PPM means part per million usually a measure of quality.
  注: PPM是百万分之一件的缩写通常是质量的一种指标.
  
• Objective : To study implement effect of PPM - tuberculosis control project in city.
  目的: 探讨在城区实施PPM-DOTS项目的效果情况.
  
• Meters such as the PPM were not specifically designed to measure loudness.
  来自BBC