[
  {
    "sentence": "Yo estoy _____ con mi amigo. (hablar)",
    "correct": "hablando",
    "distractor": "hablado",
    "explanation": "-ar verbs form the gerund with -ando.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  },
  {
    "sentence": "Ella está _____ pizza. (comer)",
    "correct": "comiendo",
    "distractor": "comendo",
    "explanation": "-er verbs form the gerund with -iendo.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  },
  {
    "sentence": "Estoy _____ un libro. (leer)",
    "correct": "leyendo",
    "distractor": "leiendo",
    "explanation": "Vowel-stem: i becomes y to avoid three vowels.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  },
  {
    "sentence": "Los niños están _____. (dormir)",
    "correct": "durmiendo",
    "distractor": "dormiendo",
    "explanation": "Stem-change o→u in the gerund of dormir.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  },
  {
    "sentence": "Él está _____ la verdad. (decir)",
    "correct": "diciendo",
    "distractor": "deciendo",
    "explanation": "Stem-change e→i in the gerund of decir.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  },
  {
    "sentence": "Nosotros _____ trabajando ahora.",
    "correct": "estamos",
    "distractor": "somos",
    "explanation": "Progressive uses estar (action right now), not ser.",
    "source_chapter": "06",
    "source_title": "The Present Progressive"
  }
]