| 摘要 |
<p>The control grid is for use in bingo or other games of chance. It consists of a mask with a removable small round concealed numbers. The master chart can be placed over the card being checked, to compare the numbers on the card with those called out. The concealed spaces for the numbers are formed by covering with a paper, cardboard or plastic sheet (2) with round cutouts (3) and removable flap (1). Adjacent flaps are separated by strips (4) of the base material to form a matrix of numbers.</p> |
