A baseball player strains to throw a ball.
The player cannot throw a ball.
If a player strains to throw a ball, it is because it is able to do it.
exists e1 p1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_strain(e1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_throw(e2) & n_ball(x3)) & n_player(x1) & of(x1,x2) & n_baseball(x2))
exists x1.(n_player(x1) & -exists e1 p1.(exists e2 x2.(Theme(e2,x2) & Actor(e2,x1) & v_throw(e2) & n_ball(x2)) & Topic(e1,p1) & Actor(e1,x1) & v_can(e1)))