No acid rain has fallen in the region. The annual level of suspended particulate matter in the urban atmosphere averages 340 microgram per cubic meter a day,well within state standards.是什么意思_No acid rain has fallen in the region. The annual level of suspended particulate matter in the urban atmosphere averages 340 microgram per cubic meter a day,well within state standards.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句