So it is very necessa ry to reduce the frictional resistance c oefficient in order to raise gas flow an d reduce running cost.A lot ...是什么意思_So it is very necessa ry to reduce the frictional resistance c oefficient in order to raise gas flow an d reduce running cost.A lot ...在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句