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

Example Input: In pupa stage of their life cycle do insects begin developing their wings.
Example Output: In what stage of their life cycle do insects begin developing their wings?

Example Input: Stringed instruments can help show the relationship between tension and frequencies in strings.
Example Output: Stringed instruments can help show the relationship between tension and what in strings?

Example Input: The oldest fossil of land plants date back 470 million years many millions of years.
Example Output:
The oldest fossil of land plants date back how many millions of years?