| 摘要 |
A blackboard eraser including a cube having two semi-cylindrical grooves symmetrically arranged in a longitudinal direction therein, and a central brush atop an elevated surface formed between the two grooves. A longitudinal groove is defined underneath each of the send-cylindrical grooves, and equal-length side brushes, which are affixed to an inner surface of a lid, are respectively positioned in the longitudinal grooves. Two grooves are arranged adjacent to each end of the semi-cylindrical grooves, which provide for a shaft affixed to each end of a roller to dispose therein. The brushes and the rollers form the eraser, which are enclosed within a closed chamber between the lid and the two semi-cylindrical grooves. When erasing chalk dust from a blackboard, the chalk dust sticks to the rollers and is carried to the side brushes. The side brushes then wipes the dust, which falls into the closed chamber.
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