RESEARCH METHODThe stratified multi-stage cluster random sampling method was used in the survey.

研究方法本研究采用分层整群随机抽样方法进行抽样。

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RESEARCH METHODThe stratified multi-stage cluster random sampling method was used in the survey.

研究方法本研究采用分层整群随机抽样方法进行抽样。

youdao