A person riding a bike with blue wheels on a tree trunk at night.
It is night
The condition of time of is established in the first sentence and the second through repetition;  At night, a person rode a bike with blue wheels on a tree trunk.
exists e1 s1 x1 x2 x3 x4 x5 x6 x7.(a_topic(x1) & at(e1,x7) & n_night(x7) & on(e1,x5) & n_trunk(x5) & of(x5,x6) & n_tree(x6) & with(e1,x4) & n_wheel(x4) & a_blue(s1) & Theme(s1,x4) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_bike(x3) & (x1 = x2) & n_person(x1))
exists p1 x1.(n_thing(x1) & exists x2.((x1 = x2) & n_night(x2)))