People are busy shopping at a grocery store.
A group of people peruse items at a grocery store
People involves a group, being plural and in one location. Shopping always requires perusing items. So, this is a necessary condition.
exists p1 x1 x2 x3.(at(p1,x2) & n_store(x2) & of(x2,x3) & n_grocery(x3) & exists s1 x4.((x1 = x4) & n_shopping(x4) & a_busy(s1) & Theme(s1,x4)) & n_people(x1))
exists e1 x1 x2 x3 x4 x5.(at(e1,x4) & n_store(x4) & of(x4,x5) & n_grocery(x5) & Theme(e1,x3) & Actor(e1,x1) & v_peruse(e1) & n_item(x3) & of(x1,x2) & n_people(x2) & n_group(x1))