HE DIFFICULTY in learning a foreign language lies not only in its inherent complexity. Languages are complex in different ways (though all are learnable by infants). The main reason a language is hard is that it is different from your own.
America’s State Department places the languages it teaches diplomats into four categories (see chart), with estimates of how long they take to learn them ranging from 24 to 88 weeks. What underlies the difficulty of such languages for an English-speaker?