Primarily these holes are for draining out the water above the slab into the drain. Since drains run through low lying area water tends to flow over the slab also. You can even identify if the drain has clogged, by seeing the water coming up these holes,
TradeSNS易之家呼吁广大网友遵守网络相关法律法规、严禁发布各类敏感不实信息；
同时TradeSNS易之家将严厉打击各类不法传播活动和违法有害信息，构建和谐的网络空间。