It's impossible to give you just two specific plates, as there are many mid-ocean ridges around the world, each separating different pairs of plates. For example:
* The Mid-Atlantic Ridge separates the North American and Eurasian plates in the North Atlantic and the South American and African plates in the South Atlantic.
* The East Pacific Rise separates the Pacific and Nazca plates.
* The Mid-Indian Ridge separates the African and Indo-Australian plates.
So, to give you the answer you're looking for, you need to tell me which mid-ocean ridge you're interested in!
