Methods:A stratified cluster sample of 212 junior middle school students was investigated with a self-made questionnaire.
方法：采用分层整群抽样方法，对武汉市某中学212名初一、二学生进行自编的初中生性知识性态度问卷调查。
Methods: an anonymous questionnaire was completed on a stratified cluster sample of 1735 elementary school and middle school students who were randomly selected from Hegang.
方法：分层随机整群抽取鹤岗市1735名中小学生进行无记名问卷调查。
Methods: Stratified random cluster sampling method was used to determine the survey sample.
方法：以分层随机整群抽样的方法，确定调查样本。
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