| 摘要 |
For the purposes of arranging moulded blocks (20, 21) alternately in horizontal and vertical array, the blocks (20, 21) are also provided with projections and/or recesses in the region of the side surfaces (25, 26) so that they may alternately engage with corresponding projections and/or recesses in the top (23), bottom (24) or sides (25, 26) of adjacent blocks. |
