This is a very newbie-ish question, so bare with me. Let's say the guitar plays an Asus, G2, D, Bm7, Bm9, (Key D) etc... How do you determine what to play with these chords? I'm assuming I'd play a D when the guitarist plays a D chord, but I'm confused with the rest. I've played bass for a while, but typically by ear (and not very well). I've picked up a few books that I'm working through, but still on the search for a good instructor. Care to help me out a bit?