[
  {
    "sentence": "Yo _____ de México.",
    "correct": "soy",
    "distractor": "estoy",
    "explanation": "Place of origin uses ser.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "Ella _____ doctora.",
    "correct": "es",
    "distractor": "está",
    "explanation": "Occupation uses ser; no indefinite article needed.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "Nosotros _____ amigos.",
    "correct": "somos",
    "distractor": "estamos",
    "explanation": "Identity (we are friends) uses ser.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "_____ las tres de la tarde.",
    "correct": "Son",
    "distractor": "Es",
    "explanation": "Hours 2 and up are plural → son.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "_____ la una en punto.",
    "correct": "Es",
    "distractor": "Son",
    "explanation": "1 o'clock is singular → es la una.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "La fiesta _____ en mi casa.",
    "correct": "es",
    "distractor": "está",
    "explanation": "Where an event TAKES PLACE uses ser, not estar.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "Tú _____ muy alto.",
    "correct": "eres",
    "distractor": "estás",
    "explanation": "Physical trait → factual → ser.",
    "source_chapter": "05",
    "source_title": "The Verb Ser"
  },
  {
    "sentence": "Yo _____ feliz hoy.",
    "correct": "estoy",
    "distractor": "soy",
    "explanation": "Emotion that changes over time → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "¿Dónde _____ tú?",
    "correct": "estás",
    "distractor": "eres",
    "explanation": "Location → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "Las puertas _____ abiertas.",
    "correct": "están",
    "distractor": "son",
    "explanation": "Current condition → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "Él _____ alto.",
    "correct": "es",
    "distractor": "está",
    "explanation": "Physical trait → factual → ser.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "Nosotros _____ en el parque.",
    "correct": "estamos",
    "distractor": "somos",
    "explanation": "Location → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "Tú _____ ocupado ahora.",
    "correct": "estás",
    "distractor": "eres",
    "explanation": "Temporary condition right now → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "Hoy _____ nublado.",
    "correct": "está",
    "distractor": "es",
    "explanation": "Weather adjective → estar.",
    "source_chapter": "07",
    "source_title": "The Verb Estar"
  },
  {
    "sentence": "La puerta está _____ (cerrar).",
    "correct": "cerrada",
    "distractor": "cerrado",
    "explanation": "Puerta is feminine; participle agrees.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "El libro está _____ (abrir).",
    "correct": "abierto",
    "distractor": "abrido",
    "explanation": "Abrir has irregular participle 'abierto'.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "Los textos están _____ (escribir).",
    "correct": "escritos",
    "distractor": "escribidos",
    "explanation": "Irregular 'escrito', plural masculine.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "La cama está _____ (hacer).",
    "correct": "hecha",
    "distractor": "hacida",
    "explanation": "Hacer→hecho; agrees with feminine cama.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "El problema está _____ (resolver).",
    "correct": "resuelto",
    "distractor": "resolvido",
    "explanation": "Resolver has irregular 'resuelto'.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "Mis respuestas están _____ (completar).",
    "correct": "completas",
    "distractor": "completados",
    "explanation": "Respuestas is feminine plural.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "El día está _____ (morir).",
    "correct": "muerto",
    "distractor": "morido",
    "explanation": "Morir has irregular 'muerto'.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  },
  {
    "sentence": "El _____ Día de los _____.",
    "correct": "Muertos",
    "distractor": "Muerto",
    "explanation": "Plural masculine: Muertos.",
    "source_chapter": "38",
    "source_title": "Past Participles As Adjectives"
  }
]