广播电视英语短句 第 296 课：种植树木-3

Traditionally the farms used windows to provide fresh air in the chicken houses. 传统的农场都是使用窗户来给鸡舍提供新鲜空气。

Farmers rarely planted trees or tall crops around the buildings, so there would be no barrier to the airflow. 农场主们很少在这些房屋周围种植树木或者较高的作物，所以没有什么可以作为气流的屏障。

But then farms began to use new ventilation systems. 但是，后来农场开始使用新型的空气置换系统。

Instead of windows, the new systems used tunnel fans to circulate air. 取代了窗户，这些新系统使用管道风扇来置换空气。

The fans directed airflow from the poultry houses toward the homes of neighbors. 这些风扇将气流从家禽鸡舍引流向邻居们的家了。