1 and the coordinate key in bG major is bE minor, and its minor key is f; If F is the main key, D will be reduced to a six-degree rising tone (the first key is #fa), then the scale to be written is F Dorian mode. Four drops of key signature.

2. The coordinate key in B major is #G minor, and the sixth sound is E; With E as the main key, D will drop to seven notes (the first key is bsi), so the scale to be written is: E mixed with Lydia mode. The key signal is 4 liters.

3. The parallel minor in 3.bD major is bB minor, and bC should be the second key of the old mode (the first key is bsi), so the scale to be written is bB Frizia mode. The key signature is five flat numbers.