oneul beoseuga neujeoseo nado jigakhaesseo.

Today the bus was late, so I was late too.

Breakdown of oneul beoseuga neujeoseo nado jigakhaesseo.

• 나: I
• ~가: subject particle
• 오늘: today
• ~도: additive particle

Questions & Answers about oneul beoseuga neujeoseo nado jigakhaesseo.

Why is the subject marker 가 used with 버스가 here? Could it be 버스는 instead?

• 버스가 marks “the bus” as the grammatical subject and presents it as new or factual information: the bus was late.
• 버스는 would make “the bus” the topic and often adds contrast or emphasis (e.g., “As for the bus (today), it was late…”).
• All of these are possible with slightly different nuance:
  • 오늘 버스가 늦어서… (plain statement of cause)
  • 오늘은 버스가 늦어서… (“today” is topical/contrastive)
  • 버스는 늦어서… (contrastive “as for the bus”)

Why is it 늦어서 and not 늦었어서? Where did the past tense go in the first clause?

• With the connective -아서/어서 (“because/so”), Korean usually puts the tense on the final verb of the sentence. So 늦어서 … 지각했어 is the normal pattern.
• 늦었어서 is generally avoided in standard usage and sounds awkward.
• If you need explicit past in the first clause, switch to a different linker:
  • 버스가 늦었기 때문에…
  • Or split into two sentences: 버스가 늦었어. 그래서…

What exactly does -아서/어서 do here? Could I use -니까 or 때문에 instead?

• -아서/어서 links a natural cause to its result and sounds neutral and matter-of-fact.
• Alternatives:
  • : often a bit stronger or more reason-giving/justificatory.