| 摘要 |
PROBLEM TO BE SOLVED: To improve the conventional complicated and consequently high cost nonpowder-flying chalk eraser. SOLUTION: A chalk eraser, the bottom surface of which has a curve so gentle that no chalk powder flies in the air, is divided into two portions or a wiping part, which worns away heavily, and a supporting part, which supports the wiping part, so as to easily exchange only the wiping part and to realize a low cost as a whole.
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