3 翻译两句话，谢谢
6 The various air pollution control devices are conveniently divided into those for controlling particulates and those used for controlling gaseous pollutants.
7 The reason,of course,is the difference in the size.
Gas molecules have diameters of about 0.0001 microns ,particulates range from 0.1 microns.
谢谢
参考答案:6.各种空气污染控制设备可以简单的划分为控制颗粒物的和用于控制气态污染物的.
7.当然,原因是尺寸大小不同.
气体分子的直径在0.0001毫米.微粒的(直径)在0.1毫米之间