I didn't think this sentence existed in Czech.
Hahaha! It's to recognize foreigners
That's an unrealistic example
Aaaaand there go all your czech friends.
Wow... Czech humour is unique. :)
"I can't stand beer" is also correct. Well, linguistically.
Contractions are accepted automatically by Duolingo. If yours wasn't, use the report button. Double or triple-check your answer first, though, most such reports contain typos and missing words.
I can't figure out how to report this properly since it isn't an option, but it seems like the accent check is no longer working and I need to come to this page to see if I got that part right.
Have a look at this discussion, in which a user recommends reporting your experience: https://forum.duolingo.com/comment/36529482.