Can anyone describe the difference between "gennem" and "ad"? Compare "Børnene går ind ad døren" versus "Jeg hører katten gennem væggen". I have the feeling that "ad" is connected to movement, while "gennem" is not. Is that true?
This is not possible any more. Duolingo removed this feature some time ago. Back in the old days this was possible when you were following someone on Duolingo. You could even send private messages to them. But now the "Follow" feature has become more or less senseless.