关于省略疑问

She was watching, her tears dried and her expression one of disbelief.Then, she reached out her hands to grasp mine. I looked up into her eyes. Shesmiled at me. "Thanks."

请问，这里的and her expression one of disbelief什么是语法成分？为何and前后又可以连接句子和名词？

her tears dried and her expression one of disbelief

and 并列二个独立主格结构作随着状语。dried在此为过去分词，不是过去式。