Lt. Bob
Spread the Daf!
can't tell without hearing the song.
Most of the replies could be correct ...... a strong case could be made for them all technically.
But you've got to hear the song to know.
I do songs in C that have the Em and Am in them. I also do things in Am that have the Em and C in them hhhmmmm .... do things in a minor key that would have the equivelent of the other two chords in them although I'm not sure if they're in Em or not.
And while it's true that most songs end on the tonic or root chord ..... there are plenty that don't.
So without any further info it's not possible to tell regardless of how the chords relate to each other.
Most of the replies could be correct ...... a strong case could be made for them all technically.
But you've got to hear the song to know.
I do songs in C that have the Em and Am in them. I also do things in Am that have the Em and C in them hhhmmmm .... do things in a minor key that would have the equivelent of the other two chords in them although I'm not sure if they're in Em or not.
And while it's true that most songs end on the tonic or root chord ..... there are plenty that don't.
So without any further info it's not possible to tell regardless of how the chords relate to each other.
we are working on a bunch of new stuff that is still beginner but hopefully a step above. I notice alot of songs like some pop kinda rock, tend to use upwards of 7 chords and even change keys!! Man........whatever happened to the good ol' fashioned 3 chord song a la Hank Williams Sr??!!! 
