Breakdown of beoseuga jiyeondwaeseo orae gidaryeosseoyo.
Questions & Answers about beoseuga jiyeondwaeseo orae gidaryeosseoyo.
버스가 uses the subject marker -가/-이, because the sentence is describing what happened to the bus: the bus was delayed.
지연되다 means to be delayed (something undergoes a delay), so 버스 is the grammatical subject of 지연되다.
If you used 버스를, it would suggest the bus is the object of some other action (like I missed the bus / I took the bus / I waited for the bus), but that’s not what this first clause is doing.
지연돼서 is a common contraction:
- Dictionary form: 지연되다 (to be delayed)
- Conjugation: 지연되어서 (being delayed, and so…)
- Contracted: 지연돼서
So 돼서 is basically 되어서 shortened (very common in spoken/written Korean).