The vent-pipe should be connected to the air outside of the residence.

灶具中的排气管用钢管或PVC 管连接通到室外大气中。

Fifthly, the best angle of vent-pipe and duct of concrete is discussed in theory.

对送风管与泵送砼管之间的最佳角度问题进行了理论探讨。