第二次平時翻譯（１－４－１˙２）

The pollutants we produce come from two types of sources.
Point sources are single,identifiable sources.
Examples are the smokestack of a coal-burning power or industrial plant,the drainpipe of a factory,and the exhaust pipe of an automobile.
我們生產來自兩種類型來源的污染物。點狀來源是唯一可識別的來源。例如燒煤或工廠的煙囪、工廠的排水管和汽車的排氣管。