Complex sentence: The two stations, Bukharestskaya and Mezhdunarodnaya of the Frunzensko-Primorskaya line, opened in December 2012, will be followed by another four heading southward-Prospekt Slavy, Dunayskaya, Balkanskaya and Yuzhnaya.
Split into simpler sentences: The two stations, Bukharestskaya and Mezhdunarodnaya of the Frunzensko-Primorskaya line, are due to open in the end of 2012. These will be followed by another four heading southward-Prospekt Slavy, Dunayskaya, Balkanskaya and Yuzhnaya.