Formal:
* 恭喜 (gung1 hei2): This is the most common and formal way to say congratulations. It literally means "congratulate" and is used for a wide range of occasions, like weddings, graduations, promotions, etc.
* 恭喜恭喜 (gung1 hei2 gung1 hei2): This is a more emphatic and celebratory way to say congratulations, often used for more special occasions.
Informal:
* 恭喜你 (gung1 hei2 nei5): This is a more casual way to say congratulations, adding "you" to the end of the formal "恭喜".
* 恭喜呀 (gung1 hei2 aa3): This is a more informal and friendly way to say congratulations.
* 恭喜晒 (gung1 hei2 sai3): This is a very informal and playful way to say congratulations, often used among friends.
Other options:
* 恭喜發財 (gung1 hei2 faat3 coi4): This literally means "congratulations and make a fortune" and is commonly used during Chinese New Year.
* 恭喜大喜 (gung1 hei2 daai6 hei2): This means "congratulations on your great joy" and is used for weddings and other auspicious events.
It's important to choose the appropriate expression based on your relationship with the person you are congratulating and the formality of the occasion.