ventilation pipe短语¹⁸⁰⁰⁹⁸⁺¹ 基本例句 风管,通风管 On the basis of analyses and researches, this paper derives a method to measure the air leakage ratio within the last 100m ventilation pipe and the air volume to be provided by the ventilation fans. 并通过分析研究，推导出末段百米漏风率的测定方法，及其计算漏风量和风机供风量的公式。 cnki