I am studying about 아/어도 되다 pattern from this site. I understand this structure and how it is used in a sentence. However, I am really curious about the word 도. Does anyone have a deep analysis why the word is used here or maybe its origin to make it have that meaning?
되다 : We are in a suitable or permitted state
도 : 보조사 auxiliary. Except the previous, it tells that there is another similar thing.
Someone A breaks the traffic rule so that policeman ask identification card. After some investigation, A talks
가도 돼요 ? Is it possible that I will go = Do you finish a report ?