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

[Q]: 10 million years long can a large star be on the main sequence stage.
[A]: How long can a large star be on the main sequence stage?


[Q]: Adding the number of protons plus the number of neutrons in an atom decides its approximate mass; atomic number is another word for this value.
[A]: Adding the number of protons plus the number of neutrons in an atom, decides it's approximate mass, what is another word for this value?


[Q]: Most turtle bodies are covered by a special bony or cartilaginous shell developed from their ribs.
[A]:
Most turtle bodies are covered by a special bony or cartilaginous shell developed from their what?