He felt people were contemptuous of his lack of sophistication.

他觉得们看不起他不世故。

She is unschooled in the way of the world.

她不世故；她丝毫不世态炎凉。

He's very young and inexperienced, and doesn't know about the ways of the world.

他还年轻, 又缺乏经验, 不得世故。