It's important to learn things about protecting environment. Here's a 5Rs rule for us. *Reduce If you want to reduce waste, you should use things wisely. A large number of trees are being cut down to make paper. If everyone uses paper carelessly and then throws it away, soon we would not have any trees left. Some other things are also being wasted, and people don't know what to do with waste in big cities, so it's necessary to reduce waste. *Reuse You should always think of reusing the usable things before throwing them away. Give your clothes or things you don't use to the poor. In a family, you may pass such clothes on to your younger brothers or sisters. *Recycle Bottles, cans and paper can easily be recycled. By doing so we save lots of time and money, for example, cola cans are sent to a factory, where they're smashed flat and smelted  , and the metal things are made into new cola cans. *Recover When you buy a box of apples, there may be a few rotten apples, you have two choice: one is to throw the whole apples away, or you should cut off the rotten parts and use the good parts. In this way, you are recovering the eatable parts of food. *Repair If one of the legs of your table is broken, you can repair it instead of throwing the table away. If you want to change for better ones, it's better for you to sell the old ones or give them to other people who can use them after doing some repair. The "Reduce" rule mainly requires us   _  .
to use things wisely to cut down many trees to use paper carelessly to use more and more things