ai

1. Asking 'Who'
Because Vietnamese has strict word order, the position of ai tells you its role:

• Subject of an action: Ai + Verb? (Who is doing the action?) -> Ai goes at the beginning.
• Object: Subject + Verb + ai? (Whom is the subject acting upon?) -> Ai goes after the verb.
• Identity: With the verb là, the position depends on what you are asking. If asking who someone is, ai goes at the end (e.g., Người đó là ai? = Who is that person?). If asking who fulfills a role, ai goes at the beginning (e.g., Ai là giám đốc? = Who is the director?).

2. Meaning 'Anyone' or 'Everyone'
Ai is also an indefinite pronoun. It can mean 'anyone' in yes-no questions (e.g., Có ai ở nhà không? = Is anyone home?), conditional clauses (e.g., Nếu ai hỏi... = If anyone asks...), and negative statements (e.g., Tôi không quen ai = I don't know anyone).

To use ai to mean 'everyone', you pair it with the word cũng (also/equally). The structure ai cũng literally means 'anyone also', which translates to 'everyone' (though you can also use standard nouns like mọi người or tất cả mọi người to mean 'everyone').

Important: When 'everyone' is the object of the sentence, Vietnamese requires object fronting. You cannot follow strict SVO order and say Tôi thích ai cũng. Instead, you can use the structure Ai + Subject + cũng + Verb (e.g., Ai tôi cũng thích = I like everyone) or Subject + ai + cũng + Verb (e.g., Tôi ai cũng thích).

3. The Relative Pronoun Trap
Do not use ai to translate 'who' in relative clauses (e.g., 'The man who called me'). In Vietnamese, relative clauses are formed differently, often using mà or simply placing the clause directly after the noun (no mà).

4. Other Common Uses

• ai đó: Means 'someone' or 'somebody' (e.g., Có ai đó đang gọi = Someone is calling).
• không ai: Means 'no one' or 'nobody' (e.g., Không ai biết = No one knows).
• Ai ai cũng: A reduplicated form meaning 'absolutely everyone'.
• Ai mà...: Used in rhetorical questions meaning 'who would' or 'nobody' (e.g., Ai mà biết được? = Who would know?). You will also see related patterns like ai mà chẳng (who wouldn't).
• ai nấy: Means 'everyone' or 'each person', often paired with đều (e.g., Ai nấy đều mệt = Everyone was tired).