A man on a very tall unicycle entertains the crowd.
A man rides the unicycle at the fair.
A man riding a unicycle to entertain a crowd is not necessarily at the fair. He could be out on the street or at some other event.
exists e1 s1 x1 x2 x3.(n_crowd(x3) & Theme(e1,x3) & Actor(e1,x1) & v_entertain(e1) & on(x1,x2) & n_unicycle(x2) & a_tall(s1) & Theme(s1,x2) & r_very(x2) & n_man(x1))
exists e1 x1 x2 x3.(n_fair(x3) & n_unicycle(x2) & at(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_man(x1))