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

Q: Gabbro is a dark dense rock that can be found in the oceanic crust.

A: Gabbro is a dark dense rock that can be found in what?
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Q: Seismologists originally measured the intensity of an earthquake with the mercalli scale.

A: How did seismologists originally measure the intensity of an earthquake?
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Q: Lab safety symbols should you learn that allows you to recognize and avoid the dangers of specific hazards when experimenting, such as flames or broken glass.

A:
What should you learn that allows you to recognize and avoid the dangers of specific hazards when experimenting, such as flames or broken glass?
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