废物回收

People plant a great number of young trees in the mountainsWhen the trees grow big and tall enough，they are cut down by workers and carried out of the mountains to the paper mill where fine paper is made from woodThen it is taken to every corner of the country and used for different purposesSome people use paper to copy writing，others use it to write something such as letters，reports and articlesWhen paper turns out to be of no use，the waste paper is collected and retreated in the recycling factory before being put into use again