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

[Q]: Water plus other substances makes a(n) solution.
[A]: Water plus other substances makes what?


[Q]: Stringed instruments can help show the relationship between tension and frequencies in strings.
[A]: Stringed instruments can help show the relationship between tension and what in strings?


[Q]: Precipitation are a natural process that allows water to return again to the earth’s surface.
[A]:
What natural process allows water to return again to the earth’s surface?