In music, the key of F, the key of A, and the key of G are all scales in music, and the major key is the structure of the scale.
F natural major is a major key based on the F note, consisting of F, G, A, ?B, C, D, E and F. The key signature has a flat.
A major is a major key based on the A note, consisting of A, B, C?, D, E, F?, G? and A. The key signature has three sharps. The parallel minor is F sharp minor and the tonic minor is A minor.
G major is a major mode with G as the central note. The parallel minor is E minor, which is counted as a sharp in the staff.
Extended information:
The interval size between each note is in the order of "whole-whole-half-whole-whole-whole-half". This is the major key. Composition rules, we divide the entire scale into two parts: "DO, RE, MIFA" "SOL, LA, SIDO", which are called "sound patterns";
Each sound pattern contains four tones. The intervals between them are all "whole, whole, half", so a major key is composed of two "whole, whole, half" tone patterns, connected by a whole tone in the middle. The oral formula composed of the entire major scale is: "whole and half, whole and half"
Baidu Encyclopedia - Major
Baidu Encyclopedia - G major
Baidu Encyclopedia—F major
Baidu Encyclopedia—A major