back-draft反向气流
back-draft damper反向通风调节风门
back area draft后区牵伸
Back Zone Draft后区牵伸
Back Draft Damper逆止风门
back draft process后区牵伸工艺
back draft change gear后牵伸变换齿轮
back draft zone后牵伸区
back-end draft窑尾通风