A-(으)ㄴ데 and V- 는데

A-(으)ㄴ데 and V- 는데

This expression has 2 usages....1. It's used when information in the second clause of the the sentence is oppsite of, in contrast, or an unexpected result of what is presented in the first. It corresponds to 'but' in English.
예(Example)1)전 남자친구가 있는데 여자친구는 없어요.
I have a boyfriend, but not a girl friend.
2)전 노래는 못 하는데 춤은 잘 춰요. I can't sing, but I can dance well.
3) 전 한국어를 쓰고 읽을 수 있는데 말을 잘 못해서 한국사람들이 무엇에 대해 말했는 지 몰랐어요.
I can write and read Korean, but I didn't know what the Koreans were talking about because I don't speak Korean well.
2. Its can used when the first clause expresses the reason or background situation for the second clause and also when the first clause provides content introducing the second clause, it corresponds to 'so/therefore' or 'and' in English.
예)
1) 추운데 창문을 닫을까요?
It's cold, so shall I close the window?
2) (이미) 많이 샀는데 이제 갈까요?
You've bought a lot already, so shall we go?
3) 겨울인데 남자친구가 없어서 전 춥고 너무 외로워요..
It's winter, and I am cold and so lonely because I don't have a boyfriend..