We don't included solids and pure liquids when solving for K because they don't have affect the concentration of the other reactants and products and does not exhibit a partial pressure. Hope that helps!
For not including liquids and solids, what if there is H2O as a gas? When I see that I'm worried that there is a typo. Also, I've noticed a few typos in the textbook so far about figure numbers which is frustrating.