水果在炎热的天气里很快会腐烂。

Fruit quickly ___decays in hot weather.

如果不加以维护，这座历史建筑的结构会慢慢腐朽。

Without proper care, the structure of this historic building will gradually ___decay.

社会道德在这个社区正逐渐腐化。

The moral standards in this community are ___decaying slowly.