题目内容：

阅读下面材料，在空白处填入1个适当单词的或括号内单词的正确形式。

Scientists found that air pollution may be responsible 1. a big reduction in 2. (intelligent). Research showed that air pollution led to big falls in test 3. (score) for languages and mathematics. The study called "The influence of air pollution on cognitive (认知的)performance"4.(conduct) over four years ago. Researchers analyzed speaking and mathematics tests 5. (take) by 20,000 people of all ages. They said, "Polluted air may do harm to cognitive ability as people become older. "

The study is a warning to the rest of the world ,6.(particular) those in cities. Over 91 percent of the world population live in areas with polluted air,7. is the fourth biggest cause of global deaths. Researchers discovered that the 8.(long) people were exposed to polluted air, the greater their cognitive ability went down. They said air pollution caused a year' s worth of lost education. For those aged over 60, this could be several years. A researcher warned, "There 9.be) no shortcut to solve this issue. Governments really need to take effective measures 10.(reduce) air pollution. "