Formal:
* 李先生 (Lǐ Xiānshēng): This is the most common and formal way to address Mr. Li. It literally translates to "Mr. Li."
Informal:
* 李老师 (Lǐ Lǎoshī): This is used if Mr. Li is a teacher. It literally translates to "Teacher Li."
* 李哥 (Lǐ Gē): This is a more casual way to address Mr. Li, especially if you are close to him or younger than him. It literally translates to "Brother Li."
* 李叔 (Lǐ Shū): This is used if Mr. Li is older than you and you are close to him. It literally translates to "Uncle Li."
Note: In Chinese, the surname (Li) comes before the given name (e.g., "Mr. Li").
Writing:
* Traditional Chinese: 李先生 (Lǐ Xiānshēng)
* Simplified Chinese: 李先生 (Lǐ Xiānshēng)
It's important to choose the appropriate title based on the specific situation and your relationship with Mr. Li.