"You girls have changed."

Translation: Voi ragazze siete cambiate.

[peterb12]

The answer given uses the conjugation "siete cambiate", but I thought cambiare only took avere in the passato prossimo. Am I mistaken?

(It does accept "avete cambiato" as an acceptable answer).

[mukkapazza]

Depends on what follows the participle of cambiare:

• Abbiamo cambiato casa - We changed/moved houses
• La casa è cambiata - The house changed
• Ho cambiato le scarpe - I changed the/my shoes
• Le scarpe sono cambiate - The shoes changed
• Mia madre ha cambiato la ricetta - My mother changed the recipe
• Mia madre è cambiata dopo la ricetta - My mother changed after the recipe

Avere requires a direct object. That simple! Here are a few examples specific to the sentence:

• Voi ragazze siete cambiate - You girls have changed
• Voi ragazze avete cambiato il colore - You girls have changed the color
• Voi ragazze l'avete cambiato - You girls have changed it
• Voi ragazze l'avete cambiata (la ricetta) - You girls have changed it

[Chris123456]

Pearls of wisdom! Great question Peter (struggled with this for a good couple of hours last night!) Brilliantly concise and explicit reply from our beloved mukkapazza. Complimenti a tutti!

[cgroothius]

Perfectly explained. Duolingo...we need some little lessons like these added in somewhere...maybe if you see a user get this wrong x times, then pop up a lesson. With a print button. Also maybe add a print button to the comments section?