1. Place 장소 가 본 데가 어디야? = 가 본 '장소'가 어디야? = Where have you been? 2. Thing to do 일, 것 이 책을 다 읽는 데 삼 일이 걸렸다. = 이 책을 다 읽는 '것에' 삼 일이 걸렸다. = It took three days to read (finish) this book. 3. In case of 경우 머리 아픈 데 먹는 약 = 머리 아픈 '경우에' 먹는 약 = The medicine for headache (in case you have headache) And most likely you don't need to use '에' after '데', so just use only '데'. I don't remember any exception for now.

I guess you're asking as 어디예요? & 어디 있어요? They both means "Where are you?", but 어디 있어요 means not only for 'you' but also other things like "Where is it?" In addition, 어디예요? = Where are you? 어디에요? = 어디에+요? = Where? └ "Oh, I forgot to bring my purse!" "어디에요?"

~께서 comes with verb for action. Like read, talk, walk, etc... ~께서는 comes with be verb "be" Like He is a teacher, He is there, etc... Of course there can be some exceptions, but normally...

I did my best... but your boyfriend should learn how to divide a sentence properly... I don't know what to do even though I'm the person who has to be changed because it's all my fault. I really wanna make you happy and be loved, and also I wanna introduce you to my close friends, but I can't express these feeling because of my bad English. I'm always wondering if I'm good enough for you, whether I'm making any mistakes, what else I can do to make you happier. But I'm stupid that I can only think but can't act like that, also don't know how to improve myself. I wanna know everything happening of your daily life, what you did, what you ate, but I don't wanna put you in my prison, and it's gonna be too much pressure for you.

Never heard about this singer group, but I just searched. - 상남자 (Boy In Luv) - No More Dream - N.O

Using any different kind of method will be helpful, but sometimes their lyrics are stupid and don't make sense even for korean. If you really enjoy listening k-pop, then it will be good, but you'd better not rely on this only.

(나는) David한테 반했어요. = I have a crush on David.

이사장님, 안돼요? 이사장님 = Mr. Lee (but '사장님' means 'boss' who is the owner of business) 안돼요? = Can't I?