As of this writing (2017-12-12, 13 days until Christmas), those of you looking at Duolingo’s notes on 줄, might find that the given definition is string or row and with 3 example sentences:
- 줄에 서 있어요. ~ I am standing in line.
- 그릴 줄 모르는 남자가 책을 차요. ~ The man who cannot draw kicks the book.
- 아들은 아빠에게 편지를 보내줄 거야. ~ A son will send a letter to the dad.
The three examples are not examples of the usage of 줄 as defined above. They are all different usages that use the 줄 spelling.
<h1>줄에 서 있어요.</h1>
Here, 줄 means line or row of people. In this usage, it is similar to the English concept of a line such a a string, connection, or queue.
<h1>그릴 줄 모르는 남자가 책을 차요.</h1>
Here, 줄 means ability (similar to 수), and it is a part of a grammatical pattern. The breakdown for the sentence is as follows (parts have been rearranged to match the English flow of the sentence):
- 남자가: the man
- ㄹ줄 모르는: who cannot
- 그리: draw
- 책을 차요: kicks the book
The grammar pattern ㄹ줄 모르다 shows inability to do something and its opposite is ㄹ줄 알다.
- 수영할 줄 알아요?: Do (you) know how to swim?
- 그는 그릴 줄 몰라요.: He does not know how to draw.
<h1>아들은 아빠에게 편지를 보내줄 거야.</h1>
Here, 줄 comes from 주다 (to give), and it is attached to another verb 보내다 (to send). The compound verb is attached to the ending pattern ㄹ 것이다 (here as ㄹ 거야) which is used to express a future intention. The breakdown for the sentence is as follows (parts have been rearranged to match the English flow of the sentence):
- 아들은: a son
- 보내줄 거야: will send
- 편지를: a letter
- 아빠에게: to the dad
주다, when attached to another verb, adds the sense of doing something for someone (maybe as a favor).
- 빨리 오세요: come quickly
- 빨리 와 주세요: come quickly (for me)
It's just a difference in how Korean speakers and English speakers conceptualize a consecutive sequence of 김밥 lined up in a single file. Koreans consider a line of individuals and a line of 김밥 pieces to be the same concept. But in English we think of: a line of people when the line is independent; a row of people when the lines of people are a part of a two-dimensional structure; but a roll of 김밥 because the 김밥 is one unit (which is cut, but undivided) formed by rolling, and is served/sold as a unit.
My point is… different languages are not on the same page. There are languages which make finer distinctions and languages which conceptualize things differently. This is one of those examples.