A group of men in the water.
there are some people sunk in river
Just because people are in water doesn't mean they have sunk.  Not all bodies of water are rivers.
exists x1 x2 x3.(n_water(x3) & a_topic(x1) & of(x1,x2) & in(x2,x3) & n_man(x2) & n_group(x1))
exists p1 x1 e1 x2 x3 x4.((x1 = x2) & in(e1,x4) & n_river(x4) & Theme(e1,x3) & v_sink(e1) & (x2 = x3) & n_people(x2))