... live in cities. City (39) cause water pollution when they are poured into waterways. These wastes (40) fish and make some areas unfit for swimming. In addition, many large ( 41) have difficulty ... passage: Many cities have a serious pollution problem. Motor vehicles, factories, and other (36) create so much air pollution that it may hang in the air like dirty (37) . Air pollution (38) the ... have difficulty in disposing of their garbage. The amount of (42) grows each year, but places to put it are filling up. Citizens, government, industries, scientists, and business people must...