Thanks, all. Perikles, I will never ignore you. Even if you ask me to do so.
Hernán - for the ones with asterisks, what would be the subtleties in differences of meaning for using por or para?
Malila - I was stuck on #5.... Your comments on #11 and #20 make perfect sense to me.
#16 is idiomatic, right? We weren't given these idiomatic phrases in class, so I looked them up online somewhere. What is the sense of saying "Estar por/para..." De hecho, I didn't understand the sentence as a whole with either, so I was essentially guessing....
#17 - I didn't like either por or para there, either. It really seemed to want an "en", but the exercise was for por/para solamente.....