这个历史遗址几个世纪以来已经衰败。

The historical site has fallen into ___decay over the centuries.

如果没有保护措施，许多古迹面临衰败的风险。

Many ancient monuments are at risk of falling into ___decay without conservation efforts.

城市基础设施的逐渐衰败给现代城市带来了挑战。

The gradual ___decay of urban infrastructure poses challenges for modern cities.