一...都唔/冇

This pattern is a 'workhorse' of colloquial Cantonese for adding emphasis to negative statements. It follows a specific structure where the emphasized unit (whether an object, a measure, or a degree like 一啲 jat1 di1 or 少少 siu2 siu2) is placed before the verb or adjective:

1. Subject Placement: The subject usually comes before the '一 + classifier' block (e.g., 我一個都冇買 ngo5 jat1 go3 dou1 mou5 maai5 - 'I didn't buy a single one'). If the noun is fronted as a topic, the subject can follow it (e.g., 蘋果我一個都冇買 ping4 gwo2 ngo5 jat1 go3 dou1 mou5 maai5 - 'Apples, I didn't buy a single one').
2. Optional Emphasis: You can add 連 (lin4) ('even') immediately before the emphasized unit to make the negation stronger (e.g., 我連一個都冇買 ngo5 lin4 jat1 go3 dou1 mou5 maai5 - 'I didn't even buy one'). While double-emphasizing both the subject and the degree in the same sentence is generally avoided as clunky, it can occasionally be used for dramatic effect in highly colloquial speech. Usually, to emphasize the subject, say 連我都唔知 (lin4 ngo5 dou1 m4 zi1 - 'even I don't know'), and to say 'I don't know at all', use 我一啲都唔知 (ngo5 jat1 di1 dou1 m4 zi1).
3. The Unit: Starts with 一 (jat1) followed by a classifier. While a classifier is usually required for countable nouns (e.g., 個 go3), some nouns function as their own measure (e.g., time or action words like 日 jat6 - 'day' or 次 (ci3 - 'time'), as in 我一次都冇去過 ngo5 jat1 ci3 dou1 mou5 heoi3 gwo3 - 'I haven't been a single time'). For uncountable things, adjectives, or countable nouns in a plural or non-specific sense, use 啲 (di1) (e.g., 我一啲蘋果都冇買 ngo5 jat1 di1 ping4 gwo2 dou1 mou5 maai5 - 'I didn't buy any apples at all'). The phrase 少少 (siu2 siu2) is also frequently used interchangeably with 一啲 for uncountable nouns or degrees (e.g., 我少少都唔驚 ngo5 siu2 siu2 dou1 m4 geng1 - 'I'm not scared even a little bit'). If a noun is used, it is usually placed immediately after the classifier and before the focus marker 都 (dou1) (e.g., 我一個蘋果都冇買 ngo5 jat1 go3 ping4 gwo2 dou1 mou5 maai5 - 'I didn't buy a single apple'), unless it has been fronted as a topic. In colloquial speech, the noun is often omitted if the context is clear. Note that 半 (bun3 - half) can be swapped in for 一 (one) to add dramatic flair, especially with countable nouns or abstract concepts (e.g., 半個都冇 bun3 go3 dou1 mou5 - 'Not even half of one', 半句都唔講 bun3 geoi3 dou1 m4 gong2 - 'Doesn't say half a sentence / Doesn't say a word').
4. The Focus: The word 都 (dou1) acts as a focus marker, meaning 'even' or 'all' in this context.
5. The Negator & Verb/Adjective: Because the emphasized unit is placed earlier, the verb or adjective must follow the negator:

• 冇 (mou5) + Verb: Used to negate completed actions or indicate an action didn't happen (e.g., 我一個都冇買 ngo5 jat1 go3 dou1 mou5 maai5 - 'I didn't buy a single one'). For possession, 冇 acts as a standalone verb at the end of the pattern (e.g., 我一毫子都冇 ngo5 jat1 hou4 zi2 dou1 mou5 - 'I don't have a single cent'). Warning: Never use 冇 with adjectives in this pattern (e.g., 一啲都唔好 is correct; 一啲都冇好 is wrong).
• 唔 (m4) + Verb/Adjective: Used for general actions, habits, or stative verbs/adjectives (e.g., 佢一個字都唔識 keoi5 jat1 go3 zi6 dou1 m4 sik1 - 'He doesn't know a single word'; 一啲都唔驚 jat1 di1 dou1 m4 geng1 - 'Not scared at all').
• 未 (mei6) + Verb: Used for things that haven't happened yet (e.g., 我一啖都未食 ngo5 jat1 daam6 dou1 mei6 sik6 - 'I haven't eaten a single bite yet').
• 唔好 (m4 hou2) / 咪 (mai6) + Verb: Used for negative commands or prohibitions (e.g., 一個都唔好買 jat1 go3 dou1 m4 hou2 maai5 / 一個都咪買 jat1 go3 dou1 mai6 maai5 - 'Don't buy a single one').

Note that Cantonese speakers frequently attach the experiential aspect marker 過 (gwo3) to the verb when using 冇 or 未 to negate actions in this pattern (e.g., 我一個都未食過 ngo5 jat1 go3 dou1 mei6 sik6 gwo3 - 'I haven't eaten a single one yet').
6. Forming Questions: To turn this pattern into a question, typically add 係咪 (hai6 m4 hai6) before the phrase (e.g., 你係咪一個都冇買？ nei5 hai6 m4 hai6 jat1 go3 dou1 mou5 maai5? - 'Did you really not buy a single one?').