a kayaker tumbles over.
A person on a kayak tumbles over while on dry land.
Tumbling over can take place on a wet land too, not only on a dry land..
exists e1 s1 x1.(a_over(s1) & Manner(e1,s1) & Actor(e1,x1) & v_tumble(e1) & n_kayaker(x1))
exists e1 s1 s2 x1 x2 x3.(on(e1,x3) & n_land(x3) & a_dry(s2) & Theme(s2,x3) & r_while(e1) & a_over(s1) & Manner(e1,s1) & Actor(e1,x1) & v_tumble(e1) & on(x1,x2) & n_kayak(x2) & n_person(x1))