Crow perishing with thirst saw a pitcher, and hoping to find water, flew to it with delight.

When he reached it, he discovered to his grief that it contained so little water that he could not possibly get at it. He tried everything he could think of to reach the water, but all his efforts were in vain.

Necessity is the mother of invention.It tells us ,when we have troubles ,we can't give up .Like the crow ,it successed at last.So we must look for the keys to the troubles.If we give up at once,we won't success!