I have tried without spaces between the first symbol and the colon and with a space but I always seem to get these particles incorrect even with the correct symbols.
I feel it is slightly unfair and a recoding of the text checker would help, but, does anyone know how this should be spaced just so I can get by.
In regards to your concern, I’m not exactly sure if typing just one of characters would work in the mobile version but in the case of desktops (which I am using), I just type in one of the given items and memrise passes it of as correct. Although this doesn’t resolve the problem of answering with both given items at once, my suggestion is (in my opinion) time saving and more convenient.