"What do you eat fish with?"
Translation:З чим ви їсте рибу?
"What do you eat with fish?"" asks what kind of food you like to pair with fish. "What do you eat fish with?" could be asking the same question, though it sounds a bit strange, but it could instead be asking if you use a fork or a knife or something else to eat fish.
Oh, no, that would be "Чим ви їсте рибу?".
"З чим ви їсте рибу?" means "What do you eat fish with?" more in the sense of "with lemon juice" or "with this and that sauce".
The meaning is very close, but I guess here the focus is on the grammatical structure?..
Hm so in Ukrainian there are definitely two different questions: "Що ви їсте з рибою?" and "З чим ви їсте рибу?". To me it looks like the first one is "What do you eat with fish?" and the second one is "What do you eat fish with?" or "With what do you eat fish?"
I might be wrong and it could be that these two sentences mean the same thing, but at least in my Ukrainian mind the sound different :D
In this particular sentence, no. The word з always takes the Instrumental case e.g. з котом, з мамою, з ким, з ним.
"З" means "with". The phrase "З днем народження" is basically a chopped-off sentence coming from "Вітаю тебе з днем народження" (literally, I congratulate you with your birthday).
It sounds quite unnatural to me.... I wouldn't say it. It sounds like an excerpt from an old poem :)