For each wff find an interpretation in which it is true and

For each wff, find an interpretation in which it is true and one in which it is false.

Ans(a):

say, Domain = all dinosaurs

then TRUE case is given by:

A(x) = dinosaur had two legs
B(x) = dinosaur had four legs

All dinosaurs had two legs or four legs, and no dinosaurs had both four legs and two legs.

---------------

FALSE case is given by:

A(x) = dinosaur eats meat
B(x) = dinosaur eats plants

All dinosaurs ate meat or ate plants, and no dinosaurs ate both meat and plants.