A man doing some roofing work on a very steep roof.
A man is biking on a roof.
You can do roof work but you cannot bike on a roof.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_do(e1) & on(x3,x5) & n_roof(x5) & a_steep(s1) & Theme(s1,x5) & r_very(x5) & n_work(x3) & of(x3,x4) & n_roofing(x4) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_roof(x2) & Actor(e1,x1) & v_bike(e1) & n_man(x1))