A crowd stands, waiting for a subway.
A crowd gathers around a drummer as they wait for a train.
The crowd might stand apart, instead of "the crowd gathers." There is no mention of a drummer. The crowd is waiting for a subway, not a train.
exists e2 e1 x1 x2.(for(e1,e2) & for(e2,x2) & n_subway(x2) & Actor(e2,x1) & v_wait(e2) & Actor(e1,x1) & v_stand(e1) & n_crowd(x1))
exists e1 x1 x2 x3 x4.(for(e1,x4) & n_train(x4) & Actor(e1,x1) & v_wait(e1) & around(x1,x3) & as(x3,x1) & n_thing(x1) & n_drummer(x3) & n_gather(x1) & of(x1,x2) & n_crowd(x2))