Examples
yóu yú由于mǒu xiē某些yuán yīn原因，tā她kàn qǐ lai看起来hěn很yōu shāng忧伤。
由于某些原因，她看起来很忧伤。
She looks blue for some reason.
开心时，书可以给你增加快乐；忧伤时，书可以给你减少哀愁。
When you are cheerful, books can increase your happiness; when you are sad, books can lessen your sorrow.