佛罗里达州经常出现塌陷坑，因为那里的石灰岩地基容易被地下水溶解。

Florida frequently experiences ___sinkholes due to its limestone bedrock being easily dissolved by groundwater.

那家健身房简直就是个无底洞，会员费高昂却几乎没有像样的设备。

That gym turned out to be a ___sinkhole, charging high membership fees while offering almost no decent equipment.