Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[EX Q]: Ultrasound, a diagnostic technology, uses high-frequency vibrations transmitted into any tissue in contact with the transducer.
[EX A]: What diagnostic technology uses high-frequency vibrations transmitted into any tissue in contact with the transducer?

[EX Q]: Digestion begins in the gastrovascular cavity.
[EX A]: Where does digestion begin?

[EX Q]: Limestone is insoluble in water, so acid can dissolve it.
[EX A]:
Limestone is insoluble in water, so what can dissolve it?