[
  {
    "sentence": "Ayer yo _____ con mi amigo. (hablar)",
    "correct": "hablé",
    "distractor": "hablo",
    "explanation": "Yo preterite of hablar = hablé (with accent).",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Tú _____ una pizza anoche. (comer)",
    "correct": "comiste",
    "distractor": "comes",
    "explanation": "Tú preterite of comer = comiste.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Ella _____ en Madrid el año pasado. (vivir)",
    "correct": "vivió",
    "distractor": "vive",
    "explanation": "Él/ella preterite of vivir = vivió.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Nosotros _____ en el restaurante ayer. (comer)",
    "correct": "comimos",
    "distractor": "comamos",
    "explanation": "Nosotros preterite of comer = comimos.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Ellos _____ todo el día. (trabajar)",
    "correct": "trabajaron",
    "distractor": "trabajan",
    "explanation": "Ellos preterite of trabajar = trabajaron.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Yo _____ tres millas esta mañana. (correr)",
    "correct": "corrí",
    "distractor": "corro",
    "explanation": "Yo preterite of correr = corrí.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Tú _____ la carta. (escribir)",
    "correct": "escribiste",
    "distractor": "escribes",
    "explanation": "Tú preterite of escribir = escribiste.",
    "source_chapter": "25",
    "source_title": "Past Tense for Regular Verbs (Preterite)"
  },
  {
    "sentence": "Ayer yo _____ al cine.",
    "correct": "fui",
    "distractor": "iba",
    "explanation": "Preterite of ir = fui (completed action). 'Iba' is imperfect.",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "La fiesta _____ muy divertida.",
    "correct": "fue",
    "distractor": "era",
    "explanation": "An event that happened — use the preterite of ser (fue).",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "Nosotros _____ a la playa el sábado.",
    "correct": "fuimos",
    "distractor": "vamos",
    "explanation": "Preterite of ir = fuimos. 'Vamos' is present.",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "Tú _____ doctor antes, ¿verdad?",
    "correct": "fuiste",
    "distractor": "fue",
    "explanation": "Tú preterite of ser = fuiste.",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "Ellos _____ al supermercado anoche.",
    "correct": "fueron",
    "distractor": "fueran",
    "explanation": "Preterite of ir, ellos form = fueron.",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "_____ difícil aprender español.",
    "correct": "Fue",
    "distractor": "Era",
    "explanation": "Completed evaluation of an event — preterite of ser (fue).",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "¿A dónde _____ tú anoche?",
    "correct": "fuiste",
    "distractor": "fueras",
    "explanation": "Preterite of ir, tú form = fuiste.",
    "source_chapter": "26",
    "source_title": "Past Tense of Ser and Ir"
  },
  {
    "sentence": "Ayer yo _____ que trabajar mucho. (tener)",
    "correct": "tuve",
    "distractor": "tení",
    "explanation": "Preterite of tener uses tuv- stem: tuve.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Nosotros _____ en la playa el verano pasado. (estar)",
    "correct": "estuvimos",
    "distractor": "estábamos",
    "explanation": "Preterite of estar uses estuv-: estuvimos. 'Estábamos' is imperfect.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Yo _____ las llaves en la mesa. (poner)",
    "correct": "puse",
    "distractor": "ponía",
    "explanation": "Preterite of poner uses pus-: puse.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Ellos me _____ la verdad. (decir)",
    "correct": "dijeron",
    "distractor": "dijieron",
    "explanation": "j-stem verbs take -eron, not -ieron: dijeron.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "¿Qué _____ tú anoche? (hacer)",
    "correct": "hiciste",
    "distractor": "hizo",
    "explanation": "Tú preterite of hacer = hiciste.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Ella _____ un pastel para mi cumpleaños. (hacer)",
    "correct": "hizo",
    "distractor": "hico",
    "explanation": "Él/ella form of hacer is hizo (with z) to preserve the soft sound.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Yo _____ tarde a la fiesta. (venir)",
    "correct": "vine",
    "distractor": "vení",
    "explanation": "Preterite of venir uses vin-: vine.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Nosotros _____ comida a la fiesta. (traer)",
    "correct": "trajimos",
    "distractor": "traímos",
    "explanation": "Preterite of traer uses traj-: trajimos.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Tú _____ el coche al taller. (conducir)",
    "correct": "condujiste",
    "distractor": "conduciste",
    "explanation": "Preterite of conducir uses conduj-: condujiste.",
    "source_chapter": "27",
    "source_title": "Irregular Verbs in the Past - Part 1"
  },
  {
    "sentence": "Yo no _____ ir a la fiesta. (poder)",
    "correct": "pude",
    "distractor": "podía",
    "explanation": "Preterite poder = pude (managed to / could). 'Podía' is imperfect.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Ayer yo _____ que estás casado. (saber)",
    "correct": "supe",
    "distractor": "sabía",
    "explanation": "Preterite saber = supe and means 'I found out'. 'Sabía' = 'I knew (already)'.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Ellos _____ ocho horas anoche. (dormir)",
    "correct": "durmieron",
    "distractor": "dormieron",
    "explanation": "dormir is a 3rd-person stem-changer: o→u in ellos: durmieron.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Ella _____ una hamburguesa. (pedir)",
    "correct": "pidió",
    "distractor": "pedió",
    "explanation": "pedir is a 3rd-person stem-changer: e→i in él/ella: pidió.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Yo _____ a mi amigo en la calle. (ver)",
    "correct": "vi",
    "distractor": "ví",
    "explanation": "Preterite ver = vi (no written accent).",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Yo te _____ un regalo. (dar)",
    "correct": "di",
    "distractor": "dí",
    "explanation": "Preterite dar = di (no written accent).",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Él _____ el periódico esta mañana. (leer)",
    "correct": "leyó",
    "distractor": "leió",
    "explanation": "leer takes y in 3rd person: leyó.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Yo _____ al tenis ayer. (jugar)",
    "correct": "jugué",
    "distractor": "jugé",
    "explanation": "-gar verbs change yo to -gué: jugué.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Yo _____ español por dos horas. (practicar)",
    "correct": "practiqué",
    "distractor": "practicé",
    "explanation": "-car verbs change yo to -qué: practiqué.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Yo _____ a estudiar a las ocho. (empezar)",
    "correct": "empecé",
    "distractor": "empezé",
    "explanation": "-zar verbs change yo to -cé: empecé.",
    "source_chapter": "28",
    "source_title": "Irregular Verbs in the Past - Part 2"
  },
  {
    "sentence": "Cuando era niño, _____ al parque todos los días.",
    "correct": "iba",
    "distractor": "fui",
    "explanation": "Habitual past action → imperfect of ir.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Mientras yo _____, sonó el teléfono.",
    "correct": "comía",
    "distractor": "comí",
    "explanation": "Background ongoing action → imperfect.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Cuando éramos jóvenes, nosotros _____ en Madrid.",
    "correct": "vivíamos",
    "distractor": "vivimos",
    "explanation": "Habitual past → imperfect of vivir.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "_____ las cinco cuando llegó.",
    "correct": "Eran",
    "distractor": "Fueron",
    "explanation": "Time in the past always uses imperfect of ser.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Mi abuela _____ mucho la tele.",
    "correct": "veía",
    "distractor": "vio",
    "explanation": "Habit → imperfect of ver.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Yo _____ hablando cuando entró.",
    "correct": "estaba",
    "distractor": "estuve",
    "explanation": "Past progressive needs estar in the imperfect.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Él _____ muy alto de joven.",
    "correct": "era",
    "distractor": "fue",
    "explanation": "Trait/description → imperfect of ser.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Tú siempre _____ pan en la panadería.",
    "correct": "comprabas",
    "distractor": "compraste",
    "explanation": "'Siempre' + habitual action → imperfect.",
    "source_chapter": "31",
    "source_title": "Imperfect Tense"
  },
  {
    "sentence": "Ella ya _____ salido. (haber)",
    "correct": "había",
    "distractor": "ha",
    "explanation": "Past perfect uses imperfect haber 'había'.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "Yo ya _____ estudiado.",
    "correct": "había",
    "distractor": "habría",
    "explanation": "Yo form is 'había' in imperfect.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "Nosotros _____ visto la película.",
    "correct": "habíamos",
    "distractor": "hemos",
    "explanation": "Nosotros form 'habíamos' for past perfect.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "Antes de llegar, yo ya _____ comido.",
    "correct": "había",
    "distractor": "he",
    "explanation": "Past perfect with antes de.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "Él no me lo _____ mostrado.",
    "correct": "había",
    "distractor": "habrá",
    "explanation": "Negation goes before haber, which stays imperfect.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "I had a dog (state) → Yo _____ un perro.",
    "correct": "tenía",
    "distractor": "había tenido",
    "explanation": "Ongoing past state uses imperfect of tener.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "I had to study → Yo _____ que estudiar.",
    "correct": "tuve",
    "distractor": "había",
    "explanation": "Completed obligation uses preterite of tener.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  },
  {
    "sentence": "Antes de ir al trabajo, me _____ duchado.",
    "correct": "había",
    "distractor": "habíamos",
    "explanation": "Reflexive 'me' before haber, yo form 'había'.",
    "source_chapter": "40",
    "source_title": "Past Perfect Tense"
  }
]