During an experiment，a scientist placed a shark into a large pool and then put several small fish into the pool as well.As expected.jye.ai shark quickly swam around the pool and attacked（攻擊） the small fish.Unluckily，（1）

none

none

of them remained alive and all were eaten up by the shark.
   The scientist then put a strong piece of glass into the pool，which （2）

divided

divided

the pool into two parts.The shark was on one side of the glass and she then put a group of new fish on the other side.The shark quickly attacked the small fish again.Soon，the shark hit the glass really hard and （3）

repeated

repeated

this behaviors many times.Well，the fish just swam around and weren't hurt at all.Finally，about an hour later，the shark stopped and left the fish alone.
   This experiment went several times over the next few weeks.Each time，the shark got less aggressive（好斗的）.Finally，the shark was not（4）

interested

interested

in hitting the glass anymore as if no fish were around.
   The scientist then took the glass out，but the shark （5）

still

still

refused to attack.The shark was trained to believe there was a strong piece of glass there，so the fish swam wherever they liked，completely free from any danger.
   Like the shark，many of us will stop trying after experiencing some failures for the（6）

purpose

purpose

of protecting ourselves.We believe that we will always be unsuccessful after we fail some times.In other words，we continue to see a barrier（障礙） in our mind even when there is no" real" barrier（7）

between

between

where we are and where we want to go.Everyone has a dream and the road to achieving it is filled with challenges and problems.We should always regard them as chances to improve ourselves and believe they can not defeat（打?。?us（8）

but

but

make us stronger.What we are supposed to do is to think wisely and try hard，and the hope is around the corner.