ai cũng

This pattern relies on the mandatory inclusion of the adverb cũng (also/too). Literally, it means 'Whoever it is, they also...', which translates to 'everyone'. This is part of a broader formula where a question word followed by cũng creates a universal meaning (e.g., đâu cũng, gì cũng).

1. As a Subject:
When "everyone" is the subject doing the action, use the structure: Ai cũng + Verb / Adjective. For extra emphasis, you can optionally add đều (all/equally) after cũng: Ai cũng đều + Verb / Adjective.
Example: Ai cũng biết. (Everyone knows.) / Ai cũng bận. (Everyone is busy.)

2. Tense Markers and Modals:
Tense markers (đã, sẽ, đang) and modal verbs (phải, nên) modifying the action are placed after cũng and before the verb. However, the negative phrase không phải precedes ai cũng to mean 'not everyone' (see Section 4).
Example: Ai cũng đã biết rồi. (Everyone already knows.)

3. As an Object (object fronting):
If "everyone" is the object of your sentence (e.g., "I like everyone"), you cannot put ai cũng at the end of the sentence. You must move ai before the verb. It can go at the absolute front (Ai + [Subject] + cũng + Verb) or right after the subject ([Subject] + ai + cũng + Verb). If there is a preposition, it must move to the front along with ai.
Examples: Ai tôi cũng thích. or Tôi ai cũng thích. (I like everyone. Note: Ai tôi cũng thích is strictly unambiguous, whereas Tôi ai cũng thích can technically also mean 'Everyone likes me' depending on context.) / Với ai tôi cũng nói chuyện. (I talk to everyone.)

4. Negation:
To say "nobody" as a subject, the standard and most natural way is to use không ai + Verb. While you can technically negate ai cũng by placing không after it (Ai cũng không + Verb), this is a highly emphatic alternative that can sound unnatural if used as the default.
Partial Negation: To say "not everyone", you must place không phải before ai cũng: Không phải + ai cũng + Verb / Adjective. This is a classic learner trap, as students often mistakenly use Ai cũng không (Nobody) when they mean 'Not everyone'. Example: Không phải ai cũng biết. (Not everyone knows.)
For negating an object, the standard neutral way is Tôi không thích ai (cả/hết) (I don't like anyone). Fronting the object as in Ai tôi cũng không thích is highly emphatic, meaning 'I dislike absolutely everyone'.

5. "Anyone":
In affirmative English sentences, "anyone" also translates to ai cũng. For example, Ai cũng có thể làm được. (Anyone can do it). Additionally, a very common set phrase is Ai cũng được, which translates to "Anyone is fine." However, in negative sentences or questions, "anyone" drops the cũng and reverts to just ai. For example: Có ai ở nhà không? (Is anyone home?).

6. Heavy Emphasis:
For heavy emphasis, you can add bất cứ (any) to the front of the pattern: Bất cứ ai cũng... (Absolutely anyone/everyone...). Another highly common way to show maximum emphasis is the reduplicated form ai ai cũng (absolutely everyone).

7. Conditional/Relative Structure:
A very common structure is Ai + Verb 1 + cũng + Verb 2, where ai is the subject of the first verb, and that clause acts as a condition for the second verb. For example: Ai nhìn cũng thích. (Everyone who sees it likes it).

8. Colloquial Alternative:
In casual conversation, a highly common equivalent to ai cũng is ai mà chẳng or ai mà chả + Verb (literally 'Who wouldn't...?').

Nuance: While mọi người refers to a group collectively, ai cũng has a distributive, emphatic feel, highlighting that every single individual shares the trait. Additionally, native speakers frequently add cả or hết at the end of these sentences to reinforce the 'all/entirety' aspect (e.g., Ai cũng biết hết, Ai tôi cũng thích cả).