V/A+ 겠거니 하다

It is attached to the stem of an action verb or a descriptive verb to show the speaker presumes or concludes that one, of course, will do so.

쉽겠거니 하고 시험 공부를 늦게 시작했는데 너무 피곤해서 잠이 들고 말았어요.
I started studying for the exam late because I thought it would be easy, but I fell asleep because I was so tired.

회의 시간을 알고 계시겠거니 하고 말씀드리지 않았어요.
I didn’t tell you because I thought you might know the time of the meeting.

가벼운 감기이겠거니 하고 병원에 안 갔더니 증세가 심해졌어요.
I didn’t go to the hospital because I thought it might be a mild cold, and the symptoms got worse.

Conversation:

누구의 에스엔에스(SNS)인데 그렇게 열심히 보고 있어?
Who’s SNS(Social Network Service) is it that you are watching it so hard?
응, 내가 좋아하는 가수 거야. 그 가수가 요즘 너무 바빠서 게시물을 못 올리겠거니 했는데 날마다 올라오네.
Ah, it’s my favorite singer. I had thought he couldn’t do posting since he is so busy these days, but it’s coming up every day.
요즘 연예인들은 공연하랴, 에스엔에스(SNS) 관리하랴 정말 몸이 두 개라도 모자라겠어.
Performing, and managing their SNS, I think even two bodies would not be enough for celebrities these days.
맞아. 에스엔에스(SNS)가 팬들과 소통하는 중요한 공간이니까 소홀히 할 수 없지.
That’s right. They can’t neglect SNS because it’s an important space to communicate with their fans.
어떤 사람들에게 에스엔에스(SNS)는 더 이상 사적인 영역이 아닌 공식적인 공간이 된 것 같아.
For some people, SNS seems like an official space, not a private area anymore.
그렇지. 자신의 정치적 신념을 전하는 정치인들은 물론이고 일반인이 자기를 알리려고 할 때도 에스엔에스(SNS)를 이용하니까.
Yeah. Not only politicians who deliver their political beliefs, but common people also use SNS to make themselves known.

Related words
소통 communicate
사적 personal
영역 area
신념 belief
공식적 official

Source: Yonsei University. Korean Language Institute