【环境保护】阅读图文材料，回答下列问题。

近向年，在我国抽样城市调查中，郑州市的空气污染指数居高不下，多次位列城市空气污染严重排列榜首位。（见下表）请简要分析郑州近几年来空气污染严重的原因，你认为哪些有效措施能够缓解郑州市空气污染的问题？

    It's very important that we all recycle. In nature, everything can be1again. For example, when an animal dies, it becomes 2animal's food. Nothing is wasted. But humans have created things like plastic bags 3can't be broken down by nature. Our rubbish kills animals and 4water and soil. 5we continue making too much rubbish, the problem will only get worse. If nature can't reuse the rubbish, we must recycle6.

    We should clean up the rubbish we've made because nature can't.

    Recycling is also the right thing to do for another reason. The earth is rich in natural materials like water and trees,7these materials are not endless. We use up our natural materials much8than the earth is able to reproduce them. For example, each year we cut9more that 6,000 square miles of forest. But it takes about 25 years 10a new tree to grow.

    Recycling can help us save the earth, so let's take action right now.