Many cultures find that English might possibly be one of the most difficult languages to learn. Not, in fact, for its words, but for the fact that it has so many unusual and contradictory rules.
From the page: "Children whose father's vocabulary was more varied when they were 2 years old had more advanced language skills at age 3. Surprisingly, the dads spoke less and asked fewer questions than the mothers, suggesting it was not how much they spo