I learned some Arabic at school. They said "Mobtadaa" and "Khabar" should be "Marfou3". In this sentence بَیْروت is "Mobtadaa" and عاصِمة is "Khabar" and "Marfou3" means the words which ( ُ ) or ( ٌ ) are placed on their last part and sometimes it is irregular like مُعَلِّمانِ and مُعَلِّمونَ. The question is that this case is regular and it is not "Marfou3". So I'm confused and I'm not sure if duolingo is wrong or my learning method at school was wrong. I would be grateful if any native Arabic speaker could help me with this.