题目内容：

阅读下面材料，在空白处填入适当内容（不多于3个词汇）或括号中词汇的正确形式。

The amount and brightness of light from towns and cities around the world is at such a high level that it is reducing the darkness of night. Once upon a time, when night fell, we1.(leave) in darkness. Things are different today. A study2.(publish) in the journal Science Advances reports that artificial light at night is increasing3.(rapid) in most countries worldwide. Scientists say it grew by 2.2 percent a year4.2012 and 2016. The overuse of artificial light at nighttime is causing us many5.（problem）. According to the International Dark-Sky Association, it is affecting not only our view of the universe, but also our environment, our 6.(safe), and our health. Artificial light is a threat to our 7. (nature) environment. It threatens animals that are active at night. It has ecological effects 8.many creatures, including humans, and may reshape the entire social ecological system. Many environmentalists thought the9.(introduce) of LED lights would help the planet. However, cities are using more LED lights because they are cheaper,10.is adding to the light pollution.