المشاركة الأصلية كتبت بواسطة om.ryan

هذا السوال من أي محاضرة وكيف طريقة حله ؟؟


33) Most people know about air pollution (n) in big cities, but they`re just beginning to learn about the many (.........) (n) that we have inside buildings. fill the gap choosing one of the following options