Subject and object questions: Who saw you? / Who did you see?

Rules

• Rule 1: Subject questions

  If the answer is the person or thing doing the action, Who / What is the subject. Don't use do / does / did; the verb is like in a positive sentence. (Only for strong emphasis can we say *So who DID break it?*; a normal question has no did.)

  Pattern: Who / What + verb (past / -s)

  Example: Who ate the cake? – Ayşe ate it.

  Example: What happened?

• Rule 2: Object questions

  If the answer receives the action, make a normal question: do / does / did + subject + base verb.

  Pattern: Who / What + do / does / did + subject + base verb

  Example: What did Ayşe eat? – She ate the cake.

  Example: Who do you visit on Sundays?

• Rule 3: Subject questions in the present

  In subject questions, Who is treated as singular, so the verb takes -s.

  Pattern: Who + verb-s

  Example: Who wants some pizza?

  Example: Who plays the drums in your band?

Common mistakes

• What did happened? → What happened?

  What is the subject → no did.

• Who did break the vase? (asking for the breaker) → Who broke the vase?

  When you ask about the doer, don't use did.

• Who you saw? → Who did you see?

  Object questions need did + base verb.