Answer:
The key of E. There are a few options for the second combination listed!
Explanation:
If you can provide a few more chords for the second key, I can narrow it down for you. I've attached an example of the current options!
The introduction of Bach to music had quite an impact. Before Bach, many were ill - tempered and most became well - tempered after Bach. Harmonically speaking, Back's composition were way ahead of time. He introduced unexpected chord changes. He also initiated the keyboard technique that is still used up to date.
Element of what?? Principle of what ???