Most of the time, that question is linked with kicking people or party dispersion.

Instead of asking such an intimidating question right off the bat. I assign out roles and duties quickly on top of briefly running thru the encounters. If I appear less intimidating to people or appear immediately to be more accommodating to those new to encounter, these players feel more comfortable in telling me they don't know the fights very well. This increases my odds of successfully completing the encounter because I now know who can do what and who can't and give out the necessary information to get mechanics handled properly. Does not guarantee successful runs but definitely increases my chances of one.

Coming out bluntly and firstly with,"Who doesn't know this fight" is fairly intimidating if not too intimidating.