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

Example Input: The earth's magnetic poles have switched places repeatedly in the past.
Example Output: The earth's magnetic poles have done what repeatedly in the past?

Example Input: Light retains its original color under water because frequency remains the same when light is refracted.
Example Output: Light retains its original color under water because what remains the same when light is refracted?

Example Input: By 8 weeks, all major organs start developing.
Example Output:
By how many weeks do all major organs start developing?