Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Gabbro is a dark dense rock that can be found in the oceanic crust.

Answer: Gabbro is a dark dense rock that can be found in what?


Question: Once a plant cell becomes specialized, divide can they no longer do.

Answer: Once a plant cell becomes specialized, what can they no longer do?


Question: The speed of sound depends on medium.

Answer:
The speed of sound depends on what?