How we cite our quotes: (Chapter.Paragraph)
Quote #4
The ship's computers were bright enough to help him get the hang of the switch from his fluent Spanish to Portuguese. It was easy enough to speak, but so many consonants were left out that understanding it was hard. (6.11)
Ender's fluency in Spanish marks him as a sort of half and half outsider to Lusitania—not entirely a local, but able to make himself understood. It's interesting too that Ender can talk but not listen and understand. He does an awful lot of talking in this book.
Quote #5
"You win with her, too. It's the most she's said to anyone outside the family in months." (7.147)
Quara's silence outside the family indicates the extent to which the family is cut off from the rest of the community. Ender makes her open up and replaces her father; when the family is healed or whole, then they can talk to others.
Quote #6
His words were an accusation, but his voice spoke of wistfulness, even forgiveness, even consolation. I could be seduced by that voice. That voice is a liar.
[…]
"Calling for you was a mistake. I'm sorry." Her own voice sounded flat. Since her whole life was a lie, even the apology sounded rote. (8.31-33)
Her lies have poisoned Novinha's ability to use language. She can't apologize, and she can't tell truth when she hears it (since Ender always speaks truth.) Though, on the other hand, Novinha's life is a lie—it's in a book of fiction.