One morning I wasted nearly an hour watching a tiny ant carry a huge feather.Several times，it __1__ several obstacles(障碍物)in its path.And after a momentary pause it would make the necessary detour(绕道). At one point, the ant had to cross a crack about 10 mm wide.After some __2__ thoughts，the ant laid the feather over the crack，walked across it and picked the feather up on the other side，then continued on its way.I was __3__ by the cleverness of this ant.It was only a small insect，lacking of __4__ yet equipped with a brain to reason，explore, discover and overcome. But this ant, like the other twolegged creatures __5__ on the earth, also shares human failings.
