Only if the gas pressure were above the maximum value allowed by regulations (400 mm.W.C.) would it be necessary to install a pressure reducer on the gas pipeline outside the heating plant.是什么意思_Only if the gas pressure were above the maximum value allowed by regulations (400 mm.W.C.) would it be necessary to install a pressure reducer on the gas pipeline outside the heating plant.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句