阅读理解。
      It is well known that the Japanese people's love of fish is almost as a bee's interest in honey. As fish
populations were decreasing, fishing companies were forced to fish further and further away from the shore.
Then they had a big challenge－how to keep the fish fresh for longer. So they decided to keep the fish
stored in freezers on the boats. But the public did not like frozen fish. So again the fishing companies had
a new bigger challenge. What they decided to do was to have fish tanks on their boats. After catching fishes,
they would put them in the tanks and keep them living there until they got back to shore. But in this protected
environment, lacking predators (掠食者), the fish stopped moving around. The Japanese public felt these
dull fish did not taste fresh, which had an unpleasant effect upon sales. Once again the fishing companies
had an even bigger challenge.
     Stop for a minute! Before we go any further, I would like to ask "What are your challenges? How do you
handle an unexpected challenge?" May I think it this way that you should try to attack your challenges?
Conquer them with a Swiss Army knife. Take the most proper and simple tool that you can adopt to deal
with your situation. 
     Now back to our story. How did the Japanese finally figure out the fresh fish problem?Sharks! You
might think the same. Sharks were caught and put into the tanks with other fishes. Don't sharks eat fish?
Well, they do eat a few fish, but they did also keep more fish active alert (警觉的). The fish stay fresh
because they are challenged.
     Now, try to keep yourself fresh by finding your own shark to offer yourself a challenge in your own
business and career.