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现在许多老师都经常咳嗽,主要是他们天天擦黑板,一呼吸,就把粉笔灰吸进鼻子里去了,可不擦黑板又不行呀。别急,快使用我发明的黑板吧!
Many teachers now often cough, mainly because they wipe the blackboard every day. As soon as they breathe, they inhale the chalk dust into the nose, but they can not wipe the blackboard. Do not worry, I use the invention of the blackboard!