Many large cities are anything but beautiful.Streets are littered with trash.In this trash,however,(1).If people want to solve the problem of waste,(2).They must work out ways of making use of good things which are just thrown away as waste. When a car gets too old, it may not run any more.But if the metal that the car was made of is still good,(3).When a bottle is empty,it goes out in the trash. But bottle glass can be ground into sand and used to pave streets. Besides,garbage from food can be changed into fertilizer. But first you have to pick out all the glass and metal.Furthermore, garbage can also be a good source for making building blocks, which are then covered with concrete. Now,(4).Some day, people will watch films in a great cinema which has been built out of garbage. Future buildings, roads, and cities may be made from garbage. But so far,(5).