instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Limestone is insoluble in water, so acid can dissolve it.
answer:
Limestone is insoluble in water, so what can dissolve it?


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


question:
320 million years many years ago did early amniotes diverge into two groups.
answer:

How many years ago did early amniotes diverge into two groups?