Interesting quiz. Re Czechoslovakia: until 1948, the official language was 'Czechoslovak', as you have it, although this was never a language per se, but more of a political concept intended to unify the Czechs and Slovaks. In 1948, Czech and Slovak were adopted as the two official languages of Czechoslovakia and so they remained until the Czech Republic and Slovakia became two sovereign states in 1993. That's a very long way of saying that you might allow 'Czech and Slovak' as an answer, as well 'Czechoslovak'.