Make up sentences from the words. 1) many/ busiest/ international/ world/ in/ the/ years/ for/ heathrow/ has/ airport/ been/ the/ . 2) is/ countries/ the/ made/ individual/ up/ of/ the/ flags/ of/ union/ three/ of/ the/ kingdom's/ jack/ . 3) part/ of/ the/ lreland/ has/ 1921/ been/ kingdom/ since/ united/ northem/ a /.
Northern Ireland has been a part of the United Kingdom since 1921