Funny, these birds. We work with Lucy day-in, day-out on saying names of things: corn, pepper, nut, apple, kiwi, pear. We work on phrases like "pretty girl" and "good girl". We work on greetings-- "Hey, Big Daddy" or "Hey, Girl" -- and bye-byes. She has picked up "apple" out of those words, but few of the others.
So tell me why, when Lucy interjected a sound into a conversation last night, and I replied "Absolutely right, Lucy", she repeated that immediately. It wasn't perfectly clear, but the number of syllables, rhythm and intonation were absolutely right.