Formal:
* 生氣 (shēng qì): This is the most general and neutral way to say "angry" or "mad" in Chinese. You can use it to describe someone being angry at someone or something.
* 生氣於 (shēng qì yú): This literally means "to be angry at/with." It's a more formal way to express being mad at someone.
* 對…生氣 (duì ... shēng qì): This means "to be angry at..." and is more specific than 生氣.
Informal:
* 氣 (qì): This is a more casual and direct way to say "mad" or "angry." It's often used when someone is slightly annoyed or upset.
* 生氣 (shēng qì): As mentioned above, this can also be used in a more informal context.
* 生某人的氣 (shēng mǒu rén de qì): This means "to be mad at someone" and is more specific than simply saying 生氣.
Example:
* 我對他生氣了。(Wǒ duì tā shēng qì le.) - I'm mad at him.
* 他生氣於她的行為。(Tā shēng qì yú tā de xíngwéi.) - He's angry at her behavior.
* 我氣死了！(Wǒ qì sǐ le!) - I'm so mad!
The choice of which phrase to use depends on the level of anger you want to express and the context of the situation.