| 摘要 |
PROBLEM TO BE SOLVED: To prevent powder of chalk attached to a blackboard wiper from scattering to attach to clothes, or aspirate from the nose and to use the wiper during a lecture for a long period of time. SOLUTION: A cloth 2 for replacement is stretched over the wiping surface of a blackboard wiper 1, and a cover 3 is fixed on the wiper 1 by means of screw rod 4. For using the wiper, a cloth 2 for replacement, such as corduroy, is prepared. When a blackboard cannot be cleaned well, the rod 4 and cover 3 are detached to remove an unusable cloth to replace it with a new cloth prepared. And the used cloth is washed with water and dried for reuse.
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