I feel nervous talking in front of many people.句子结构看不懂.

I feel nervous talking in front of many people.句子结构看不懂.
这里的feel是系动词吗?是的话feel nervous 就构成句子的谓语.那后面的talking… 又是什么结构?
所以像 when i am talking in front of many people 这样的状语从句可以写成
talking in front of many people