1. She gave expression to her sadness.
    她流露出了悲伤之情.

2. I only knew it felt a little like sadness but heavier than that.
    我只知道这种心情有点像悲哀，但又比悲哀更沉重。

3. I knew my sadness came not only from missing my family, but also from the frustration of being unable to learn.
    我知道我的难受不仅仅是因为想念家，而且是因为自己无法集中精力学习而感到的沮丧。