Last time you said you would give me a list of countries.

Question

It would be great if you can list list the feminine countries and masculine and countries, the major cities in each country, also if you can, could you also list the languages spoken in those countries? thanks so much.

Another question i had last time is that I know the preposition for masculine and feminine countries using en or au. But I don't know if this makes a difference, what i want to say is that, for example, "In Canada, we study hard." The "In Canada" is Canada in general, not necessarily a prepositon, would that be au also?