positive ventilation

• 强制通风,压力通风

positive ventilation的用法和样例：

例句

1. What's the requirement for the forced ventilation system for crankcase?
   发动机曲轴箱强制通风的要求？
2. All automobile engines now built are equipped with the positive-crankcase ventilation system of crankcase emission control.
   所有现代制造的汽车发动机，都需要装备控制曲轴箱有害污染的曲轴箱强制通风系统。