A guard is on the look out while on duty.
A security guard calls in sick.
A guard cannot be one that calls in sick and be on duty at the same time
exists p1 s1 x1 x2 x3.(n_look(x3) & on(p1,x2) & n_duty(x2) & r_while(p1) & a_out(s1) & Manner(p1,s1) & on(x1,x3) & n_guard(x1))
exists e1 x1 x2 x3.(in(e1,x3) & n_sick(x3) & Actor(e1,x1) & v_call(e1) & n_guard(x1) & of(x1,x2) & n_security(x2))