There are a few questions about past vs. passed, but it seems to me that this is very much a subtle matter, where small changes can change the answer, so here is yet another one.
If you were to say, "Go past/passed the store, then take a left.", would it be past or passed?
A friend of mine insists that it is passed, but I disagree. She is so convinced that it is passed that she believes I am being willfully ignorant. I am not an expert in the English language, so it's possible that I'm wrong, but it would be a surprise to me if I were. So, StackExchange, what's the verdict? Who's right?