22. If xPx were true in a given model, it would be true of:

(a) everything in the UD (b) everything whatsoever (c) everything in P (d) nothing (e) None of the above

23. If x(Px Qx) were true in a given model, which of the following sentences would have to be false in that model?

(a) x(Px Qx) (b) x(Px Qx) (c) x(Px Qx) (d) x(Px Rx) (e) None of the above

24. If x([Px Qx] Rx) were false in a given model, which of the following could not be true?

(a) Extension(P) = (b) Extension(Q) = (c) Extension(R) = (d) UD = {Peg} (e) None of the above

25. Which of the following sentences, if true, would make x(Px Qx) false?

(a) x(Px Qx) (b) x(Px Qx) (c) Pa Qb (d) xPx (e) None of the above