这件旧外套被虫蛀得几乎不能穿了。

The old coat was so moth-eaten that it was barely wearable.

moth-eaten 是由 moth（蛾子）和 eaten（eat 的过去分词）组成的复合形容词。moth 指"蛾子"，eaten 表示"被咬、被蛀"。 moth-eaten 字面意思是"被蛾子蛀过的"，引申为"破旧的、被虫蛀坏的"，形容衣物因虫蛀而破损的状态。