I have never seen a thing, until recently, like someone not marking a cross on a multiple choice test just because he didn't know the answer.
I wonder whether this is a East Asian right-thing-to-do mentality, or just a quirk of some student.
Should maybe we ask all students to do this? Indeed, on a multiple choice with 5 choices per question, it isthe expectancy of a given that any student, no matter whether he is as thick as brick, employing pure guessing would at least get abe a 20% gradescore. But is it cheating to mark something when you don't know the answer? At least, you are getting sometimes some point for nothing.