In 1988 , Mary Andersen was at the Miami airport checking in for a flight to Norway to be with her husband when she was told she wouldn't be able to check her luggage without paying a $ 100 surcharge （超载）．                
Mary had no money as her new husband had left for Norway and she had no one else to call．
"I was completely desperate and tried to think which of my things I could manage without．" says Mary．          
As tears ran down her face, a voice behind her said, "That's okay, I'll pay for her．"
Rather surprised, Mary turned around to see a tall man whom she had never seen before．He had a gentle and kind voice mat was firm and decisive．                     
Although this happened twenty years ago, Mary still remembers the authority that radiated （发出）from the man, Mary was pleased to bring her luggage to Norway and told the stranger she would give his money back．The man wrote his name and address on a piece of paper he gave to Mary．She thanked him repeatedly When she finally walked off towards the boarding gate, he waved goodbye to her．
That man turned out to be Barack Obama．      
Mary paid the money back to Obama the day she joined her husband．At that time he had just finished his job as a poorly paid community worker in Chicago, and had started his law studies at Harvard University.        
In the spring of 2006 Mary’s parents heard Obama was considering a run for president. They wrote a letter saying that they would support him. At the same time, they thanked Obama for helping their daughter 18 years earlier.
And Obama replied, “ I want to thank you for the lovely things you wrote about me and for reminding me of what happened at Miami airport. I’m happy I could help her then, and I’m delighted to hear that your daughter is happy in Norway. Please send her my best wishes. Sincerely, Barack Obama, United States Senator.”
56．Why did Mary feel completely desperate?                                 
A．She had missed the only flight to Norway．
B．Her new husband abandoned her suddenly．
C．She didn't have the money to buy a ticket．
D．She had no money to pay for the surcharge．
57．How did Mary feel when someone offered to help her"?
A ．Amazed．           B．Puzzled．     C．Delighted．          D．Annoyed．
58．Mary asked the stranger to leave his name and address____,
A．in order to contact him later                   B．so that she could repay him
C．because impressed her deeply         D．because she fell in love with him
59．What’s the passage mainly about?                         
A．A letter from Barack Obama．                         
B．Mary's parents support Obama．                       
C．Obama helped a stranger about 20 years ago．
D．Mary was lucky to get help at the airport．