烟尘的排放量主要受到燃烧方式等因素的影响，煤在煤粉锅炉上燃烧几乎是完全的，排放的烟尘里几乎全是灰粉。
参考答案：对
________ by the advances in technology, many farmers have set up wind farms on their land.[ ]
A．Being encouraged
B．Encouraging
C．Encouraged
D．Having encouraged
瓦罗的《论农业》
