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。

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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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So, the classes of T-cells: macrophages, natural killer cells, these are a class of cells that's particularly important called dendritic cells.

这类T淋巴细胞包括巨噬细胞,自然杀伤细胞等 统称为树突细胞,树突细胞尤为重要

耶鲁公开课 - 生物医学工程探索课程节选

Without boring you in academia, one of the assumptions in the theory suggests that companies and asset classes have a natural, repeating cycle in which good performance begets bad performance and vice-versa.

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With growing middle classes and a vast array of natural resources, the countries are also vulnerable in that they are still tied to the fates of other countries: China, which is also a competitor, and Brazil, which is more like a primus inter pares.

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More particularly, cooperation between the scientific community, educational policy makers, parents, researchers of Learning and Natural Sciences, teachers and the industry is sought, so that they can make changes in school classes.

UNESCO: South Eastern Mediterranean Sea Project (SEMEP)