{
  "chapter_id": "22",
  "slug": "stem-changing-verbs",
  "title": "Stem-Changing Verbs",
  "time_range_sec": [5579, 5812],
  "summary": "Stem-changing verbs modify their internal vowel in all conjugations except nosotros and vosotros. Four categories exist: e→ie, e→i, o→ue, and u→ue (jugar only).",
  "suggested_grammar_note_id": null,
  "rules": [
    {"title": "The boot pattern", "bullets": ["Stem change applies in yo, tú, él/ella/usted, ellos/ellas/ustedes.", "Nosotros and vosotros keep the original stem."]},
    {"title": "Four categories", "bullets": ["e → ie (empezar, pensar, querer, tener)", "e → i (decir, pedir, servir)", "o → ue (recordar, poder, dormir)", "u → ue (only jugar)"]},
    {"title": "Endings stay regular", "bullets": ["Only the stem vowel changes; the ending follows normal -ar/-er/-ir conjugation."]}
  ],
  "examples": [
    {"es": "Yo empiezo el trabajo a las ocho.", "en": "I start work at eight.", "tags": ["e>ie"]},
    {"es": "Tú dices la verdad.", "en": "You tell the truth.", "tags": ["e>i"]},
    {"es": "Él recuerda mi nombre.", "en": "He remembers my name.", "tags": ["o>ue"]},
    {"es": "Nosotros jugamos al fútbol.", "en": "We play soccer.", "tags": ["u>ue", "nosotros-no-change"]},
    {"es": "Ellos pueden venir mañana.", "en": "They can come tomorrow.", "tags": ["o>ue"]},
    {"es": "Yo juego un videojuego.", "en": "I play a video game.", "tags": ["u>ue"]},
    {"es": "Ella piensa en ti.", "en": "She thinks about you.", "tags": ["e>ie"]},
    {"es": "Nosotros recordamos la canción.", "en": "We remember the song.", "tags": ["o>ue", "nosotros-no-change"]}
  ],
  "vocab": [
    {"es": "empezar", "en": "to start", "pos": "verb"},
    {"es": "decir", "en": "to say", "pos": "verb"},
    {"es": "recordar", "en": "to remember", "pos": "verb"},
    {"es": "jugar", "en": "to play", "pos": "verb"},
    {"es": "pensar", "en": "to think", "pos": "verb"},
    {"es": "jugo", "en": "juice", "pos": "noun"},
    {"es": "juego", "en": "game", "pos": "noun"},
    {"es": "videojuego", "en": "video game", "pos": "noun"}
  ],
  "conjugation_tables": [
    {
      "verb": "empezar",
      "tense_id": "ind_presente",
      "forms": {"yo":"empiezo","tu":"empiezas","el":"empieza","nosotros":"empezamos","vosotros":"empezáis","ellos":"empiezan"}
    },
    {
      "verb": "decir",
      "tense_id": "ind_presente",
      "forms": {"yo":"digo","tu":"dices","el":"dice","nosotros":"decimos","vosotros":"decís","ellos":"dicen"}
    },
    {
      "verb": "recordar",
      "tense_id": "ind_presente",
      "forms": {"yo":"recuerdo","tu":"recuerdas","el":"recuerda","nosotros":"recordamos","vosotros":"recordáis","ellos":"recuerdan"}
    },
    {
      "verb": "jugar",
      "tense_id": "ind_presente",
      "forms": {"yo":"juego","tu":"juegas","el":"juega","nosotros":"jugamos","vosotros":"jugáis","ellos":"juegan"}
    }
  ],
  "exercises": [
    {"sentence": "Yo _____ a estudiar a las nueve. (empezar)", "correct": "empiezo", "distractor": "empezo", "explanation": "empezar is e→ie; the yo form is empiezo."},
    {"sentence": "Nosotros _____ al fútbol los sábados. (jugar)", "correct": "jugamos", "distractor": "juegamos", "explanation": "Nosotros doesn't take the stem change; it stays jugamos."},
    {"sentence": "Ella _____ que sí. (decir)", "correct": "dice", "distractor": "dece", "explanation": "decir is e→i; él/ella form is dice."},
    {"sentence": "Yo _____ tu cumpleaños. (recordar)", "correct": "recuerdo", "distractor": "recordo", "explanation": "recordar is o→ue; the yo form is recuerdo."},
    {"sentence": "Ellos _____ venir hoy. (poder)", "correct": "pueden", "distractor": "poden", "explanation": "poder is o→ue; ellos form is pueden."},
    {"sentence": "Vosotros _____ pronto. (empezar)", "correct": "empezáis", "distractor": "empiezáis", "explanation": "Vosotros keeps the original stem: empezáis."}
  ],
  "caveats": "OCR contained many garbled phonetic spellings (e.g., 'empar', 'koso', 'huego'); reconstructed using standard Spanish spellings."
}
