they felt excited when finding the ___abandoned ____ knife by the lake.

问题描述:

they felt excited when finding the ___abandoned ____ knife by the lake.
这句话中when后面引导的从句不是应该有单独的一套主谓结构 那么这里finding abandoned 不是谓语动词呀
求高手赐教··

when finding the abandoned knife by the lake-------这是分词结构作时间状语.可以改写成以下句子而不改变句意:
They felt excited when they found the abandoned knife by the lake.---------时间状语从句
而整个句子可以简单地成为:
They felt excited to find the abandoned knife by the lake.--------简单句