用blackboard称呼“黑板”的历史比较长了它最初所指的是“一块黑色的教师用来书写的木板或薄板”。但是,随着时间的推移,“黑板”已发生了很大的变化。一种是材料的变化,以前的水泥、木板制品已陆续变成塑料、玻璃、橡胶、金属制品等;另一种是颜色的变化,最先的黑色已变成当今的绿色 Calling blackboard “blackboard” has a long history. It was originally referred to as “a piece of wood or sheet used by a black teacher to write.” However, over the years, “blackboard” has undergone great changes. One is the material changes, the previous cement, wood products have gradually become plastic, glass, rubber, metal products, etc .; the other is the color change, the first black has become today’s green