Two workers holding up the tree look around, while the other two work hard with their shovels.
Two workers grab a drink of water, while the others are busy.
Looking around does not imply that they grab a drink of water.  Working hard with shovels does not imply that they are necessarily busy.
exists e1 s1 s2 x1 x2 x3 x4 x5 x6.(n_shovel(x6) & of(x6,x3) & n_thing(x3) & -(x5 = x5) & n_work(x5) & card_eq_2(x5) & n_look(x3) & of(x3,x4) & n_tree(x4) & a_topic(x1) & with(e1,x6) & a_hard(s2) & Manner(e1,s2) & while(e1,x5) & a_up(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_hold(e1) & r_around(x3) & (x1 = x2) & n_worker(x1) & card_eq_2(x1))
exists e1 p1 x1 x2 x3.(exists s1.(Theme(s1,x1) & a_busy(s1)) & -(x1 = x1) & n_person(x1) & while(e1,p1) & Theme(e1,x2) & Actor(e1,x1) & v_grab(e1) & of(x2,x3) & n_water(x3) & n_drink(x2) & n_worker(x1) & card_eq_2(x1))