Trying to find the counter model using abstract form, like the domain has to be variables such as D = {a} or D = {a,b} and to prove the domain we have to use either True or False, for example: p(a) = T or p(b) = F, in order to find the example of a counter model in question. I'm lost in how to do it, please help

3. Find a countermodel for each of the following wffs. a. 3x p(x)^3x q(x) = 3x (p(x)^q(x)) b. 3x 3y p(x, y) = 3x Vy p(x, y) C. Vx p(x,x) 3x Vy p(x, y)