3 . The world’s nights are getting brighter and brighter as light pollution invades darkness almost everywhere. Researchers found that Earth’s artificially lit outdoor area grew by 2% a year from 2012 to 2016. So did night time brightness. Light pollution was even worse than that, according to the German-led team, because the light sensor(感应器) cannot recognize some of the LED lighting that is becoming more widespread, specifically blue light.

“Honestly, I had hoped that with LEDs we were improving the situation. But it turns out quite disappointing.” said Kyba, the lead author of the study.

“Asia, Africa and South America, for the most part, saw an increase in artificial night lighting. More and more places are fixing outdoor lighting, due to its low cost and the growth in communities’ wealth,” the scientists said.

The biological effect from the increasing man-made light is obvious, according to the researchers. People’s sleep can be damaged, which in turn can affect their health. The living behavior of birds, fish, insects and bats can be interrupted. And forget about seeing stars or the Milky Way if the pollution continues.

“Many people are using light at night without really thinking about the cost, ” said Franz Holker, one of the co-authors. “Not just the economic cost, but also the cost that you have to pay for environmental damage.”

4 . Early people had very little effect on the environment. They lived in very small 'clan'（部落） groups. They collected or killed only enough for the clan's survival. Early clans were nomadic, which means that they did not stay in one place.     1     . The land had time to recover and animals had time to breed （繁殖） before the clan returned for the next season.   

As time went by, these small family clans joined with others to form larger groups for protection.

    2     . Eventually, people tamed（驯养） wild animals such as dogs and horses. People settled around rivers   and fertile plains to share responsibilities and duties. Then, people began to plant crops instead of moving to areas where the plants grew. This development changed the environment.

    3     . Some people were better at performing a particular task than other clan members, so they began to specialize in things they were good at doing. This also meant that they began to exchange their goods for things that others produced.

People began to communicate with distant tribes. Land was cleared for roads. Foreign plants and animals were transported to places where they had not existed before.     4     . So art, dance and music became important ways of expressing feelings and thoughts. This was how many great civilizations started.

Compared to the past, modern civilization has experienced many changes to become the highly developed society that exists today. Populations have increased rapidly. Inventions and technology have made work easier. However, pollution and other serious problems have also resulted from human progress.     5     .

5 . In our modern world, when something wears out, we throw it away and buy a new one. The _______ is that countries around the world have growing mountains of _______ because people are throwing out more rubbish than ever before.

How did we _______ a throwaway society? First of all, it is now easier to _______ an object than to spend time and money to repair it. _______ modern manufacturing (制造业)and technology, companies are able to produce products quickly and inexpensively. Products are plentiful and _______.

Another cause is our _______of disposable (一次性的) products. As _______ people, we are always looking for _______ to save time and make our lives easier. Companies ________ thousands of different kinds of disposable products: paper plates, plastic cups, and cameras, to name a few.

Our appetite for new products also ________ to the problem. We are ________ buying new things. Advertisements persuade us that ________ is better and that we will be happier with the latest products. The result is that we ________ useful possessions to make room for new ones.

All around the world, we can see the ________ of this throwaway lifestyle. Mountains of rubbish just keep getting bigger. To ________ the amount of rubbish and to protect the ________, more governments are requiring people to recycle materials. ________, this is not enough to solve (解决) our problem.

Maybe there is another way out. We need to repair our possessions ________ throwing them away. We also need to rethink our attitudes about ________. Repairing our possessions and changing our spending habits may be the best way to reduce the amount of rubbish and take care of our environment.