Fill in each blank space with a suitable word of the following passage. (dirty, threatens, wastes, pollution, recycling, products, areas, disposing, sources, garbage ) Many cities have a serious pollution problem. Motor vehicles, factories, and other (1)………….create so much air pollution that it may hang in the air like(2)……………….fog. Air pollution (3) ………….the health of the people who live in cities. City (4)……………..cause water pollution when they are poured into waterways. These waste kill fish and make some(5)……………..unfit for swimming. In addition, many large cities have difficulty(6)……………of their garbage. The amount of (7)…………..grows each year, but places to put it are quickly filling up. Citizens, gorvernments, inductries, scientists, and business people must work together to gradually reduce( 8)…………….. For example, most cities have introduced (9)……………programs, which cut down on garbageand the space needed to store it . Residents separate recyclable products from garbage, and city governments provide drop-off cites or pick up the (10)…………..from home.