Why does Mrs. Who speak using quotations?

In the
novel, , the three women, Mrs. Which, Mrs. Whatsit, and Mrs. Who, are all
stars who, after fighting the darkness in space, have come to Earth to help Meg, Calvin, and
Charles Wallace defeat the darkness and save Meg and Charles Wallace's father. They have
disguised themselves as elderly human women, but because they are really stars they have a hard
time fitting in and getting their disguises right. Mrs. Whatsit is the youngest and therefore
has the easiest time adapting, but Mrs. Who and Mrs. Which struggle a bit more. Mrs. Who, in
particular, struggles to make herself understood and so relies on quotations to get her meaning
across. She also does it in part to help keep everyone's spirits up.