Perfect Aspect Marker 'đã'

01

Basic Usage: Completed Actions

In simple sentences without other time context, đã signals that the action happened in the past. It is placed directly before the main verb.

• Tôi đã mua một cái xe mới.

  I bought a new car.

• Hôm qua trời đã mưa.

  Yesterday it rained.

• Cô ấy đã đi ngủ.

  She has gone to sleep.

02

Is 'Đã' Mandatory?

Unlike English, where verbs must change form to show the past (go → went), Vietnamese verbs remain unchanged. Time is usually established through context words like "yesterday" (hôm qua) or "last year" (năm ngoái).

If the context of the past is already clear, đã is often optional and frequently omitted in daily conversation. Using it adds a layer of emphasis or formality, stressing that the action is definitively over.

• Hôm qua tôi đi học.

  Yesterday I went to school. (Standard, relies on "yesterday")

• Hôm qua tôi đã đi học.

  Yesterday I did go to school. (Emphasizes the completion)

03

Relative Time: The "Past of the Past"

Because đã marks completion relative to a context, it is essential for expressing complex timelines. If you are telling a story about the past, and you want to mention an action that happened before that story took place (similar to the English "had done"), you use đã.

• Khi tôi đến, anh ấy đã về.

  When I arrived, he had (already) gone home.

• Lúc 7 giờ, họ đã ăn tối xong.

  At 7 o'clock, they had finished dinner.

04

Combination with 'Rồi' (Already)

To strongly express that something has "already" happened, đã is often paired with the particle rồi, which is placed at the end of the sentence. This structure (đã + Verb + rồi) is very common in spoken language.

• Tôi đã nói rồi.

  I have said it already.

• Em đã làm xong rồi.

  I have finished already.

05

Questions with 'Chưa' (Yet)

To ask if an action has been completed "yet," you combine đã before the verb and chưa at the end of the sentence.

• Bạn đã ăn cơm chưa?

  Have you eaten rice yet?

• Anh ấy đã về chưa?

  Has he come back yet?