The animals do not look aggressive.
The animals appear to be aggressive.
Do not look is the opposite of appear to be.
exists x1.(n_animal(x1) & -exists e1 p1.(exists s1.(Theme(s1,x1) & a_aggressive(s1)) & Topic(e1,p1) & Actor(e1,x1) & v_look(e1)))
exists e1 p1 x1.(n_animal(x1) & Topic(e1,p1) & Actor(e1,x1) & v_appear(e1) & exists s1.(Theme(s1,x1) & a_aggressive(s1)))