方法抽取杭州市高中学生1 185名和大学生3 200名，在健康教育干预前后进行无记名问卷调查。
Methods with cluster sampling, 1 185 senior high school students and 3 200 undergraduates were chosen. They were investigated with an anonymous questionnaire before and after the health education.
采用分层整群抽样方法，对杭州市某综合性大学的839名大学生进行匿名式问卷调查。
Methods An anonymously questionnaire survey was conducted among a random sample of 839 undergraduates.
采用分层整群抽样方法，对杭州市某综合性大学的839名大学生进行匿名式问卷调查。
Methods An anonymously questionnaire survey was conducted among a random sample of 839 undergraduates.
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