咗 / 過

Understanding the distinction between 咗 (zo2) and 過 (gwo3) is crucial for clear expression in Cantonese.

1. Duration and Present Relevance
When expressing duration, choosing between 咗 and 過 changes the implication of the action:

• 住咗幾耐 (zyu6 zo2 gei2 noi6): 'How long have you lived (here)?' — In a present context, especially with the particle 喇 (laa3), this implies you still live there. However, in a past narrative, 咗 just marks a bounded duration.
• 住過幾耐 (zyu6 gwo3 gei2 noi6): 'How long did you live (there)?' — The stay is definitively finished and you no longer live there.

2. Negation Differences
A crucial difference is how these particles behave in negative sentences:

• Negating 咗: When negating a completed action, use 冇 (mou5) and drop 咗. (e.g., 我冇食 'I didn't eat', NOT 我冇食咗).
• Negating 過: When negating an experience, use 冇 (mou5) or 未 (mei6) and keep 過. Note the difference: 未 (mei6) means 'not yet' (implying you might still do it, e.g., 我未食過 'I haven't eaten it yet'), while 冇 (mou5) is a simple statement of non-experience (e.g., 我冇食過 'I haven't eaten it').

3. Discontinuity of State for 過
The particle 過 (gwo3) indicates that an action happened in the past but its resulting state no longer holds. For example, while dying is usually permanent, you can use 過 if the state was reversed, such as in the idiom 死過翻生 (sei2 gwo3 faan1 saang1, 'to come back from the brink of death').

4. Sentence Structure: Verb-Object Phrases vs. Resultative Compounds
Both particles attach immediately post-verbally. In Verb-Object (V-O) separable phrases like 返工 (faan1 gung1, 'go to work'), the particle attaches directly to the verb root before the object: 返咗工 (faan1 zo2 gung1) or 返過工 (faan1 gwo3 gung1). In contrast, Resultative Verb Compounds (RVCs) take aspect suffixes after the entire compound, such as 打爛咗 (daa2 laan6 zo2, 'broke it').

5. Future Completion with 咗
Cantonese marks aspect rather than tense. Therefore, 咗 (zo2) does not mean past tense; it can mark a future event that will be completed before another action occurs (e.g., 聽日放咗工去睇戲 ting1 jat6 fong3 zo2 gung1 heoi3 tai2 hei3, 'Tomorrow after getting off work, I will go watch a movie').

6. Common Adverb Pairings
These particles often pair with specific adverbs to reinforce their meaning:

• 咗 pairings: Often used with 已經 (ji5 ging1, 'already'), e.g., 已經食咗 (ji5 ging1 sik6 zo2, 'already ate').
• 過 pairings: Often used with 從來 (cung4 loi4, 'never') when negated, e.g., 從來未食過 (cung4 loi4 mei6 sik6 gwo3, 'have never eaten it').

7. Colloquial Tone Change for 咗
In rapid, casual speech, the particle 咗 (zo2) is sometimes dropped entirely. When this happens, the preceding verb changes to Tone 2 to indicate the completed action (e.g., 食 sik6 becomes sik2: 我食喇 ngo5 sik2 laa3, 'I ate'). See 咗 (elided) for more details.

8. Other Functions of 過
Be careful not to assume every 過 you hear is the experiential aspect. It is a very versatile word and has other common grammatical functions, such as a comparative marker (e.g., 高過我 gou1 gwo3 ngo5, 'taller than me') or a directional verb (e.g., 行過 haang4 gwo3, 'walk over/past').

9. Imperatives and Commands with 咗
It might seem counterintuitive to English speakers, but 咗 (zo2) is frequently used in commands to urge someone to complete an action thoroughly or get rid of something. For example, 食咗佢啦！ (sik6 zo2 keoi5 laa1!, 'Eat it up!') or 掉咗佢 (diu6 zo2 keoi5, 'Throw it away!').