至於

至於 (zi3 jyu1) is a versatile conjunction used to pivot within a conversation. A fundamental constraint is that it cannot be used to introduce the very first topic of a dialogue; it requires prior context to function. While the base word is shared with Standard Written Chinese, spoken Cantonese has specific colloquial expansions (like 至於話). Its primary uses include:

• Strict Word Order: When used as a conjunction for topic shifting, 至於 must be placed at the beginning of the topic phrase, before the subject (e.g., 至於我呢，我就唔去喇 zi3 jyu1 ngo5 ne1, ngo5 zau6 m4 heoi3 laa3 - "As for me, I'm not going"). It can naturally follow other conjunctions like 但係 (daan6 hai6) to pivot to a contrasting topic (e.g., 但係至於...). Note that this strict word order rule does not apply to its secondary usage as an adverb of extent (like 唔至於), which is placed before the verb or adjective it modifies.
• Topic Shifting: Moving from one subject to a related but distinct one. For simple nouns, you use 至於, and Cantonese speakers frequently attach the topic particle 呢 (ne1) to the end of the topic phrase (e.g., 至於我呢... zi3 jyu1 ngo5 ne1... - "As for me..." or 至於錢方面呢... zi3 jyu1 cin2 fong1 min6 ne1... - "As for the money aspect..." - note that 錢 cin4 is pronounced with a standard colloquial tone change to cin2 here). While extremely common, this particle is optional and can be omitted in faster speech or more serious contexts. In colloquial speech, when introducing a clause, a claim, or an abstract concept (e.g., "As for saying we should avoid it..."), it is often expanded to 至於話 (zi3 jyu1 waa6).
• Subject Dropping: When 至於 introduces a person or thing as the topic, the subject of the following main clause is often omitted if it refers back to that same topic (e.g., 至於佢呢，就唔去喇 - "As for him, [he] is not going"), though it can also be repeated for emphasis.
• With Question Words: It is highly common to pair 至於 with question words (e.g., 至於點解, 至於幾時) or A-not-A verb structures (e.g., 至於去唔去 - "As for whether or not to go") to pivot to an unresolved issue or choice.
• Contrastive Focus: Highlighting a difference or exception. If you like most fruits but dislike one specific type, you use 至於 to introduce the exception.
• Sequential Topic Shifting: Transitioning to a specific or final item within a list or sequence of points.
• Correlative Pairing: A core structural feature of 至於 is that the following main clause almost always contains an adverb like 就 (zau6) (then) or 都 (dou1) (also/even) to complete the pivot. It is also frequently used as the final pivot in correlative lists or comparisons, such as "A is like this, B is like that, but as for C..." (A就..., B就..., 至於C就...).
• Adverb of Extent / Auxiliary Verb: As a secondary grammatical function, it is used as an adverb of degree/extent or auxiliary verb meaning "to reach the extent of" or "to go so far as to". The standard negative forms are 唔至於 (m4 zi3 jyu1) and 未至於 (mei6 zi3 jyu1). While 未 literally means "not yet", in modern Cantonese, 未至於 is heavily used as a direct synonym for 唔至於 without a temporal implication, both meaning "not to the extent of". The positive form (meaning "to the extent of") is almost exclusively used in rhetorical questions to express disbelief that a situation is that extreme (e.g., 使唔使至於咁呀？ sai2 m4 sai2 zi3 jyu1 gam3 aa3? - "Is it really necessary to go that far?", or 至於發咁大脾氣咩？ zi3 jyu1 faat3 gam3 daai6 pei4 hei3 me1? - "Is it really necessary to lose your temper like that?"). For positive statements meaning "to the extent of", speakers use 甚至 (sam6 zi3) or 去到...嘅地步 (heoi3 dou3... ge3 dei6 bou6) instead of 至於. You will also frequently hear the A-not-A question form 至唔至於 (zi3 m4 zi3 jyu1) (e.g., 至唔至於咁嬲呀？ zi3 m4 zi3 jyu1 gam3 nau1 aa3? - "Is it really necessary to be that angry?") and standalone rhetorical phrases like 至於咩？ (zi3 jyu1 me1?) ("Is it really necessary to go that far?") or 唔至於啩？ (m4 zi3 jyu1 gwaa3?) ("It's not that serious, is it?"). Structurally, this adverb/auxiliary takes a following clause, verb phrase, or pronoun like 咁 (gam3) to indicate the extent.
• Register and Formality: While 至於話 is colloquial, using 至於 by itself to pivot can sound slightly deliberate or structured. In highly casual Cantonese, speakers often drop 至於 entirely and simply use the topic particle 呢 (ne1) at the end of a noun phrase to pivot to a new topic.

Unlike 關於 (gwaan1 jyu1), which introduces the main subject of a whole discussion, 至於 is used to pivot within a discussion.