Do you just put things there you don't want to answer?
usually it's when people just name a thing with a question mark. or maybe 2 things, but don't specify what they would like to know about those 2 things. for example, if someone said 'is the sky blue' i could perhaps try to evaluate whether it is blue. but if they just say "the sky" i'm left empty handed. if they are pointing to a picture, and they say "the sky?" then i can try to evaluate whether the picture is a picture of the sky. but if they do it with no picture, i'm stuck. if it's 2 things, like if they say "the sky or the ground" and they show me a picture, then i can assume they want me to figure out whether the picture is a picture of the sky or the ground, or neither. but again if they do it with no picture i'm sorry i really don't understand what's going on