put 3 balls on each side, * X. H1 W5 {( ]4 J7 D* d
if balance, we can prove that all 6 balls on the 天平 is normal, 1 ?* `/ Y C1 Z+ U# I
if not balance, we can prove that the 6 balls outside the 天平 is normal.) M7 U% A0 ^% @. W
then use the proved-normal ball on one side and put the other ball on other side tvb now,tvbnow,bttvb5 K+ I( Y q, i1 g) X) F7 B. |, h
to determine the abnormal is heavy and light |