-거든요: This verb ending is used to add the reason of the action or situation of the speaker; however, you do not use this verb ending before stating the outcome or result of the action. It is used after. It can be replaced with '-어서/아서/해서' in an reversed order. (아직 집에 못 가요. I can't go home yet. 할 일이 많거든요. It's because there's lots of work to do.) = (할 일이 많아서 아직 집에 못 가요.) (지금 혼자 밥 먹어요. I am eating alone. 모두 다 외출했거든요. It's because everyone went out.) = (모두 다 외출해서 지금 혼자 밥 먹어요.)