* 书 (shū) This is the most common way to write "shu" and it means "book".
* 叔 (shū) This character means "uncle".
To know which character to use, you need to understand the context of the word "shu".
For example:
* "I am reading a book." would be written as "我正在书。" (Wǒ zhèngzài shū.)
* "My uncle is coming to visit." would be written as "我叔要来拜访。" (Wǒ shū yào lái bài fǎng.)
It's important to note that the pronunciation is the same for both characters, but the meaning is entirely different.