a river is

• A river is of great importance to man ' s living and production , but now the water system of natural rivers in cities is destroyed because of the rapid development of urbanization in our country , and this causes a series of environmental problems , which are being paid much attention to by the people
  摘要河流在人类的生产生活中发挥着重要的作用，但目前我国由于城市化的快速发展，城市天然河流水系遭到较大破坏，引发了一系列的生态环境问题，已经和正在受到人们的广泛关注。