方法在北京市石景山区随机整群抽取3所学校初一到高二学生1 650人，匿名自填问卷调查。

Methods an anonymous questionnaire survey was conducted among 1 650 students drawn randomly from 3 middle schools in Shijingshan County, Beijing using a clustered sampling method.

youdao

分析了北京市石景山区秋季PM _(10)质量浓度的变化特征，发现气候变化对PM _(10)质量浓度有很大影响。

This paper analyses the change of PM_ (10) mass concentration at Shijingshan District in autumn, and finds that climate change affects PM_ (10) mass concentration greatly.

youdao