A man is sitting in front of a computer monitor holding a keyboard and looking at the camera.
Someone sits in front of their computer while recording themselves singing into the camera
Sentence one doesn't mention that the man is singing while sitting for the camera. All we know is that he is holding a keyboard at the camera.
exists e1 e3 e2 x1 x2 x3 x4 x5 x6.(n_camera(x6) & for(e1,e3) & at(e3,x6) & Actor(e3,x1) & v_look(e3) & for(e1,e2) & Theme(e2,x5) & Actor(e2,x1) & v_hold(e2) & n_keyboard(x5) & in(e1,x2) & of(x2,x3) & n_monitor(x3) & of(x3,x4) & n_computer(x4) & n_front(x2) & Actor(e1,x1) & v_sit(e1) & n_man(x1))
exists e1 e3 e2 x1 x2 x3 x4 x5.(n_camera(x5) & n_group(x4) & for(e2,e3) & into(e3,x5) & Actor(e3,x1) & v_sing(e3) & while(e1,e2) & Theme(e2,x4) & Actor(e2,x1) & v_record(e2) & in(e1,x2) & of(x2,x3) & n_computer(x3) & of(x3,x1) & n_thing(x1) & n_front(x2) & Actor(e1,x1) & v_sit(e1) & n_person(x1))