eoje du siganina gongbuhaesseoyo.

I studied for as long as two hours yesterday.

Breakdown of eoje du siganina gongbuhaesseoyo.

• 공부하다: to study
• 어제: yesterday
• 시간: time
• 둘: two

Questions & Answers about eoje du siganina gongbuhaesseoyo.

What does 어제 mean?

어제 means yesterday. It’s a time adverbial that sets when the action took place, and it typically appears at the beginning of the sentence.

What is the function of -이나 in 두 시간이나? Can I omit it?

• The particle -이나 after a number shows as much as.
• In 두 시간이나, it means “as much as two hours,” emphasizing that two hours is a surprisingly long time.
• You can drop it if you want a neutral statement:
  
  • 어제 두 시간 공부했어요. (“I studied two hours yesterday.”)

How does 두 시간이나 differ from 두 시간 동안?

• 두 시간이나 uses -이나 to stress the amount (“as much as two hours”).
• 두 시간 동안 literally means for a duration of two hours, without special emphasis.
• Example:
  
  • 어제 두 시간 동안 공부했어요. = I studied for two hours yesterday. (neutral)

Why is there no subject in this sentence? How do we know who did the studying?

Korean often omits subjects when they’re clear from context. Here:

• The speaker is obviously talking about themselves, so 저는 or 제가 is dropped.
• You’d include 저는 only if you needed to contrast or emphasize:
  
  • 어제 저는 두 시간이나 공부했어요.