A couple smiling while sitting.
the man sat alone
The man can't be alone while in a couple.
exists e2 e1 x1 x2.(a_topic(x1) & while(e1,e2) & Actor(e2,x2) & v_sit(e2) & Actor(e1,x2) & v_smile(e1) & (x1 = x2) & n_couple(x1))
exists e1 s1 x1.(n_man(x1) & a_alone(s1) & Manner(e1,s1) & Actor(e1,x1) & v_sit(e1))