[
  {
    "sentence": "Yo _____ a estudiar a las nueve. (empezar)",
    "correct": "empiezo",
    "distractor": "empezo",
    "explanation": "empezar is e→ie; the yo form is empiezo.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  },
  {
    "sentence": "Nosotros _____ al fútbol los sábados. (jugar)",
    "correct": "jugamos",
    "distractor": "juegamos",
    "explanation": "Nosotros doesn't take the stem change; it stays jugamos.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  },
  {
    "sentence": "Ella _____ que sí. (decir)",
    "correct": "dice",
    "distractor": "dece",
    "explanation": "decir is e→i; él/ella form is dice.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  },
  {
    "sentence": "Yo _____ tu cumpleaños. (recordar)",
    "correct": "recuerdo",
    "distractor": "recordo",
    "explanation": "recordar is o→ue; the yo form is recuerdo.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  },
  {
    "sentence": "Ellos _____ venir hoy. (poder)",
    "correct": "pueden",
    "distractor": "poden",
    "explanation": "poder is o→ue; ellos form is pueden.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  },
  {
    "sentence": "Vosotros _____ pronto. (empezar)",
    "correct": "empezáis",
    "distractor": "empiezáis",
    "explanation": "Vosotros keeps the original stem: empezáis.",
    "source_chapter": "22",
    "source_title": "Stem-Changing Verbs"
  }
]