我们在上课时,经常看到老师用黑板擦擦黑板,虽然很少有粉笔灰落下,但是使用时间长了,粉笔灰都吸附在黑板擦上。这样,黑板擦一擦,黑板反而成了“大花脸”。老师常常到一旁的角落拍打黑板擦,抖落粉笔灰,但是效果不理想。没有办法,老师只好用抹布去擦黑板。课间休息,同学们就去帮老师抖黑板擦上的粉笔灰,可是怎么抖也抖不干净,很多灰尘已经吸附到绒里了。 When we were in class, we often saw the teacher rubbing the blackboard with a blackboard. Although there was seldom chalk ash falling, it took a long time to use and the chalk dust was adsorbed on the blackboard eraser. In this way, wipe the blackboard, blackboard instead became “big face ”. Teachers often go to the side of the corner to beat the blackboard eraser, shake off the chalk, but the effect is not satisfactory. No way, the teacher had to use a rag to wipe the blackboard. Break between classes, the students went to help the teacher shake the blackboard wipe the chalk ash, but how shake also shaking is not clean, a lot of dust has been adsorbed to the velvet.