They all refer to completed actions, but they are used differently in structure and meaning.
Đã
🧠Meaning: Did / have (past tense marker)
📍Usage Position: Before the verb
Rồi
🧠Meaning: Already / done
📍Usage Position: Ffter the verb
Xong
🧠Meaning: Finished / completed
📍Usage Position: As a verb or after an action
Tôi đã ăn sáng.
→ I ate breakfast.
Tôi ăn sáng rồi.
→ I already ate breakfast.
Tôi ăn sáng xong.
→ I finished eating breakfast.
Use “đã” to mark past tense (formal or neutral).
Use “rồi” in spoken, casual language, often with surprise or confirmation.
Use “xong” to emphasize finishing something.
🧠 Tip: You can combine them:
Tôi đã ăn sáng rồi. = Stronger confirmation: I already ate.