* Formal: 早上好 (zǎo shàng hǎo) - This is the most common and polite way to greet someone in the morning.
* Informal: 早 (zǎo) - This is a more casual and friendly greeting, often used among friends and family.
You can also use other phrases like:
* 早晨 (zǎo chén) - This is another formal greeting, slightly more literary than "早上好".
* 早上好呀 (zǎo shàng hǎo ya) - This is a slightly more friendly way to say "早上好".
The best choice depends on the context and your relationship with the person you are greeting.