Quote 19
It is a very inconvenient habit of kittens (Alice had once made the remark) that, whatever you say to them, they always purr. "If they would only purr for 'yes,' and mew for 'no,' or any rule of that sort," she had said, "so that one could keep up a conversation! But how can you talk with a person if they always say the same thing?" (Looking-Glass 12.2)
Alice wants a back-and-forth communicative exchange with her kittens. Apart from the fact that this is silly, it points out the fact that communication consists of a give and take between two parties – not just a one-sided monologue.
Quote 20
"But then," thought Alice, "shall I never get any older than I am now? That'll be a comfort, one way – never to be an old woman – but then – always to have lessons to learn! Oh, I shouldn't like that!" (Wonderland 4.10)
Perpetual youth is not only an impossibility, it doesn't even make practical sense. Would someone who was eternally young in body also be young in mind?
Quote 21
"And that's the jury-box," thought Alice; "and those twelve creatures," (she was obliged to say "creatures," you see, because some of them were animals, and some were birds,) "I suppose they are the jurors." She said this last word two or three times over to herself, being rather proud of it: for she thought, and rightly too, that very few little girls of her age knew the meaning of it at all. However, "jurymen" would have done just as well. (Wonderland 11.4)
Alice is proud, not just of knowing something, but of knowing something unusual for a child her age. But as the narrator reminds us, her knowledge isn't especially useful, so there's no reason for her to be proud.