The Polish prepositions w and z change to we and ze in front of certain consonant clusters, but I have never been able to nail down a rule as to when exactly this happens. My Polish teacher usually responds, "Well, it just depends on the speaker. Some people say we Francji and some people say w Francji." But I have a hard time believing that. And I'm continually being surprised by permissible and impermissible consonant clusters: ze Stanów, when z Stanów seems perfectly easy to me, and yet w kształcie, which I think is completely impossible to pronounce.
So - anyone out there who knows what the rule is? or whether there's a rule?