Here the answer "... in the hospital ..." is not accepted although it should be. In another exercise in this unit "... at the hospital ..." is not accepted and "in the hospital" is given as the correct answer. This kind of inconsistency needs to be ironed out of these exercises.
Is someone can enlight me about the 방금 / just now ?
In my langage, it translate like something you are doing now, so I don't really understand the past tense. Or does this (always ? ) mean that you (just) have finish what you were actually doing ? And now you are doing another thing.