| 摘要 |
A horizontal rectangularly shaped plate has a flat top surface which is enclosed by a transparent raised cover. A plurality of raised members hemispherically shaped are secured to the top surface in equidistantly spaced positions and extend upward being disposed below the inner surface of the cover. The members are disposed in rows and columns. Each two adjacent members in any row together with the two corresponding members in an immediately adjacent row define a cell with a centrally disposed region exposing the surface of the plate. One or more balls rest removably in one or more regions.
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