Boubou's language

As some of you may know, we speak French at home, and we have been from the day Levi and I met, back in 2005. Needless to say that Eve's first language is French; however, she constantly amazes us with English phrases she picks up from other children. It did not even cross my mind that she would pay attention to our conversations with grown-ups. Well, this morning, we were eating breakfast when out of the blue, Eve said (in English): "It's 5 dollars." I turned to her, after calling Levi who was in the other room, and asked her in French: "what is 5 dollars, cherie?" But, just as an oracle, she kept her peace and kept munching on a piece of toast.