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

Negative growth rate results when birth rates fall even lower than death rates.
What results when birth rates fall even lower than death rates?

Interstitial fluid are all hormones secreted into before entering the circulatory system.
Where are all hormones secreted into before entering the circulatory system?

Seismologists originally measured the intensity of an earthquake with the mercalli scale.
How did seismologists originally measure the intensity of an earthquake?