a gravelly voice的用法和样例：
- "This stuff used to be illegal," he says in a gravelly voice.
- She has lent her gravelly voice for the medieval ballads.
- "You're welcome," Billy said in his deep, gravelly voice, and I was surprised at the optimism in his tone.
- He was about sixty years old, short and thin, with a craggy face and a deep, gravelly voice he used sparingly but to great effect.