A little boy with rain boots takes a walk in the park.
a boy walks in the rain
Have on rain boots does not mean it is raining at that time.  The boy can walk in many types of weather other than rain.
exists e1 s1 x1 x2 x3 x4 x5.(n_park(x5) & in(e1,x5) & Theme(e1,x4) & Actor(e1,x1) & v_take(e1) & n_walk(x4) & with(x1,x2) & n_boot(x2) & of(x2,x3) & n_rain(x3) & n_boy(x1) & a_little(s1) & Theme(s1,x1))
exists e1 x1 x2.(n_rain(x2) & in(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_boy(x1))