A book on a table is pulled down by gravity, and the table pushes upwards on the book. Is this a third law pair?

No. The two forces in a Newton's 3rd Law pair are 1. Equal Magnitude, 2. Opposite direction. 3 Same type of force 4. Act on different objects. The two forces on the book satisfy 1 and 2 they are equal and opposite. They don't satisfy 3 as they are different types of force (one is Weight the other is Normal Contact) and they dont satisfy 4 they are on the same object not different objects.