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

Q: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only contract.

A: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what?
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Q: A covalent network solid is a compound in which all of the atoms are connected to one another by covalent bonds.

A: What is a compound in which all of the atoms are connected to one another by covalent bonds?
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Q: To increase the likelihood of accurate experiment results do scientists perform multiple trials of the same experiment.

A:
Why do scientists perform multiple trials of the same experiment?
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