Someone is in a speed boat on the water.
The speed boat is purple and green.
Not all speed boats are purple and green.
exists p1 x1 x4.(n_water(x4) & exists x2 x3.(in(x1,x2) & on(x2,x4) & n_boat(x2) & of(x2,x3) & n_speed(x3)) & n_person(x1))
exists s1 s2 x1 x2 x3.(n_boat(x1) & of(x1,x3) & n_speed(x3) & of(x1,x2) & n_speed(x2) & Theme(s2,x1) & a_green(s2) & Theme(s1,x1) & a_purple(s1))