normal bonding in a sentence

1. Scientists do n ' t know why lightning spawns x - rays . they theorize it involves a " runaway breakdown " of the air , in which electrons escape their normal bonds and gain very large energies
2. But how to fully cognition the function of rate system mechanism in employment injury insurance system , how to establish the scientifically and normal bond raising model and reasonable rate system matching our country state of the nation and the each locality of the actual circumstance has become the vital important problems
3. It's difficult to find normal bonding in a sentence.