Past-tense questions

Czech does not use a dummy auxiliary like "did" or subject-verb inversion to ask questions. Instead, past-tense questions use the exact same components as past-tense statements: the past participle and the present tense of být (for 1st and 2nd person).

Yes/No Questions:
Because Czech frequently drops subject pronouns, a standard statement often already starts with the verb. To ask a yes/no question, you can simply use a rising intonation. Yes/no questions frequently start directly with the past participle, followed by the auxiliary in the second position (e.g., Četl jsi tu knihu?), unless a subject pronoun is needed for emphasis.

Wh-Questions (Kde, Co, Proč, etc.):
Unlike yes/no questions, Wh-questions typically use a falling intonation, just like statements. The question word takes the first position. Because the auxiliary verbs (jsem, jsi, jsme, jste) are second-position clitics, they naturally follow the first-position element. When you start a sentence with a question word, the auxiliary simply takes the second position right after it. If you include a subject pronoun for emphasis, it typically comes after the auxiliary verb (e.g., Kde jsi ty byl? or Kde jsi byl ty?). While standard word order places the clitic immediately after the first element, in colloquial spoken Czech, native speakers sometimes group the question word and pronoun for heavy emphasis (e.g., Kde ty jsi byl?).

Keep in mind that question words must decline to match the case required by the verb (e.g., Koho jsi viděl? instead of Kdo jsi viděl?). Additionally, Czech does not allow leaving a preposition at the end of a sentence. The preposition must move to the front with the question word, and together they form a single unit in the first position. The auxiliary clitic must follow the entire phrase (e.g., S kým jsi byl? - Who were you with?).

• Statement: Včera jsme četli knihu. (Yesterday we read a book.)
• Question: Co jste včera četli? (What did you read yesterday?)

Important Rules:

• 3rd Person: Just like in statements, the 3rd person (he/she/it/they) takes no auxiliary verb. Never use je or jsou in the past tense. (e.g., Kde byl? - Where was he?)
• Formal 'You' (Vykání): When addressing someone formally, use the plural auxiliary jste with a singular past participle matching the person's gender. (e.g., Kde jste byl? - Where were you? [to a man] / Kde jste byla? - Where were you? [to a woman]). This uses the polite vy agreement pattern.
• Reflexive Verbs & Clitics: In the 2nd person singular, the reflexive pronouns se or si fuse with jsi to form ses or sis (e.g., Proč ses ptal?). For the 1st person singular and all plural forms, the auxiliary must always precede the reflexive pronoun in the clitic cluster (e.g., Proč jsme se ptali?). In the 3rd person, since there is no auxiliary, the reflexive pronoun simply takes the second position by itself (e.g., Proč se ptal?).
• Spoken Czech: In everyday spoken Czech, the 2nd-person singular auxiliary jsi often fuses with the question word to form an -s suffix (e.g., Kde jsi byl? -> Kdes byl?, Co jsi dělal? -> Cos dělal?).

Negative Questions:
When asking a negative question, remember that the negative prefix ne- attaches directly to the past participle, never to the auxiliary verb. This follows the standard past-tense negation rules (e.g., Proč jsi to neudělal? - Why didn't you do it?).