air quality

彰化縣埤頭鄉中和國小

The school shows a flag every morning to tell students about the air quality. 

學校每天早上會掛旗子告訴學生當天空氣品質。

The teacher is taking out a yellow flag to show that the air quality is okay. 

這位老師拿出黃旗表示空氣品質普通。