A new method applied in redox reaction

The rule for making decision by external elements instead of by internal ones is a new method to determine the direction of redox reaction by means of electromotance and electroelements. In the case of φ  oxidation state / reduction state φ  oxidation stateˊ / reduction stateˊ , the reaction is found to be : oxidation state + reduction stateˊ → reduction state + oxidation stateˊ ,i.e., the two internal elements come from the two external ones . The two internals or either of the internals or externals won' t get involved in the reaction. Such a method is simple and easy to understand and apply while superior to some other methods