The difference between ' will you do ' and ' will you be doing'?
I saw this example in the Cambridge Grammar in use, 2nd edition.
A: will you be passing the post office when you're out?
B: Probably, why?
A: I need some stamps, could you get me some?
so, I'm wondering if I can use '' will you pass the post office when you're out'', as I've known that ' will ' should be used when you decide to do sth at the time when you're speaking or when you're predicting the future, while '' be doing sth'' should be used in the situation when you've arranged to do. But in this case, 'passing the post office' has not been arranged, I know ''will be doing'' is the future continuous, but present continuous and future continuous are similar in use.
Thanks for your answers in advance.