A young girl is about to attempt to hit a tennis ball.
the girl is shooting a deer
The phrase 'about to' implies that some action is going to take place (hit a tennis ball) soon, whereas the phrase 'is shooting' implies that action is currently taking place, in this case, shooting a deer; both actions cannot be done simultaneously, and they are very different actions which take place in very different locations.
exists p1 s1 s2 x1.(Topic(s2,p1) & Actor(s2,x1) & a_about(s2) & exists e1 p2.(Topic(e1,p2) & Actor(e1,x1) & v_attempt(e1) & exists e2 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_hit(e2) & n_ball(x2) & of(x2,x3) & n_tennis(x3))) & n_girl(x1) & a_young(s1) & Theme(s1,x1))
exists e1 x1 x2.(n_girl(x1) & Theme(e1,x2) & Actor(e1,x1) & v_shoot(e1) & n_deer(x2))