A number of countries are already in the process of formulating their own standards for the control and reduction of classroom noise.
一些国家已经在着手制定本国关于控制和减少教室噪音的标准。
A number of countries are already in the process of formulating their own standards for the control and reduction of classroom noise.
一些国家已经在着手制定本国关于控制和减少教室噪音的标准。
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