下列句子中逗号有哪些用途？

I saw,with surprise and grief,the leaves fall from the trees.

Even Satan had friends,the other devils,to admire him,but I had nobody.

老师，为何有时句子用这么多的逗号，它们不是插入语，更不是同位语，更不是非限制性定语从句，是停顿的需要吗？

I saw,with surprise and grief,the leaves fall from the trees.

with介词短语为方法状语。方法状语一般应该置于宾语之后。目前插入到动词和宾语之间，前后用逗号隔开，如此，动宾结构就了解了。

Even Satan had friends,the other devils,to admire him,but I had nobody.

非限制性同位语插入宾语限制性定语之间，前后用逗号隔开。