If a guy asks you out, how do you know if he just wants to be friends?

If a guy asks you out on a one-on-one date, can you automatically assume he's interested (romantically) or does it happen that guys ask females out on one-on-one dates just to be friends??

Yeah I know, every guy is different blah blah blah, but in general?

Im talking about when you've just met someone and you're not really sure if you're just friends.... If you havent hung out with him a lot before, and he suddenly asks you to do something just the two of you,
how do you know it's a romantic date or a friendly date?

I always have this problem when meeting guys!! I can never tell if they ask me out as friends or if they're interested!! So yea, how can u tell?