A family prepares to ride on the water.
A group of people are preparing for an activity.
a family is a group and a ride is an activity
exists e1 p1 x1 x2.(n_water(x2) & Topic(e1,p1) & Actor(e1,x1) & v_prepare(e1) & exists e2.(on(e2,x2) & Actor(e2,x1) & v_ride(e2)) & n_family(x1))
exists e1 x1 x2 x3.(for(e1,x3) & n_activity(x3) & Actor(e1,x1) & v_prepare(e1) & of(x1,x2) & n_people(x2) & n_group(x1))