We selected two three-grade natural classes from Dongjing Junior Middle School in changsha, divided into the experimental class and the control class.
在长沙市洞井中学选取初三年级两个自然班，分别为实验班与对照班。
The study was designed as a quasi-experiment, taking two natural classes of the first graders in a senior high school as the subjects, experimental class and control class.
研究按照准实验来设计，采用两个高中一年级的自然、平行班级作为研究对象，一个实验班，一个对照班。
The study was designed as a quasi-experiment, taking two natural classes of the first graders in a senior high school as the subjects, experimental class and control class.
研究按照准实验来设计，采用两个高中一年级的自然、平行班级作为研究对象，一个实验班，一个对照班。
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