在防护罩表面开口透孔，且透孔宽度大于粉笔擦最大宽度。

A through hole is arranged on the surface of the hood. The width of the through hole is larger than the maximum width of a blackboard brush.

youdao

在防护罩表面开口透孔，且透孔宽度大于粉笔擦最大宽度。

A through hole is arranged on the surface of the hood. The width of the through hole is larger than the maximum width of a blackboard brush.

youdao