阅读下面短文，从每题所给的A、B、C、D四个选项中，选出能正确回答所提问题或完成所给句子的最佳答案。

     Sixteen years ago, a boy gave me an important gift. It was a smile.

      It was the early autumn of my first year at a middle school, and my old school was far away. As a result, no one knew who I was. I was very lonely, and afraid to make friends with anyone.

     Every time I heard the other students talking and laughing, I felt my heart break. I couldn't talk with anyone about my problems.

Then one day, my classmates were talking happily with their friends, but I was sitting at my desk unhappily as usual.  At that moment, a boy entered the classroom. I didn't know who he was. He passed me and then turned back. He looked at me, with a smile.

    Suddenly, I felt the touch of something bright and friendly. It made me feel happy and warm. That smile changed my life. I started to talk with other students and made friends. Day by day, I became closer to everyone in my class. The boy with the lucky smile has become my best friend now.

    One day I asked him why he had smiled, but he couldn't remember doing so!

     It doesn't matter because all the dark days have gone. I believe that the world is what you think it is. If you think it is lonely, you might always be alone. So smile at the world and it will smile back.

    When people find something valuable and return it to its owner，they are often given a reward．This is because the person not only found what was lost but also spent time finding its owner or taking it to the police station．

    There was once a young boy who found a woman's purse in a shopping center．Inside the purse there was some money and the woman's driving license．Her name and address were printed on the license，so the boy knew where she lived．That evening he went to her house and knocked on her door．When she opened it，he said，“I found your purse，''and handed it to her．

    “Thank you very much，”she said．She opened her purse and took out all the money．She wanted to give the boy a small reward，but there were only bills of$20 in the purse and she thought that$20 was too much to give the boy．“I'm sorry，”she said. “but I don't have any small change to give you．”

    The boy said，“That's all right，”and he went away．

    A few days later he found another woman's purse．It also had her driving license in it，so he knew where she lived．He went to her house and said．“l found your purse ,”and handed it to her．

    “Thank you very much，"she said．  She opened her purse and took out all her money．

    “That‘s strange，”she said．“Before I lost my purse l had a $100 bill and a $20 bill in it．Now I have a $100 bill ,a $10 bill and two $5 bills．''

    “Yes，"the boy said，and smiled．

    Ryan's life was nearly perfect. He had lots of friends on his block. They walked to school together every day, and after school they always had time to play.

    Ryan did have one problem. It was his two-year-old sister, Allie. She was too small to play ball games. She couldn't climb trees yet.  Ryan and his friends didn't want her around.

    Ryan tried asking his mum to keep Allie at home. "Why does my sister have to come along?" he asked. "Troy's sister doesn't. Jimmy's sister doesn't. Why me?"

    Ryan's mother just laughed, "Troy's sister is only six months old, and Jimmy doesn't have a sister. Allie is nice, isn't she?"

    Today, Ryan was going to play baseball with his friends after school. Allie followed him as usual. The boys used to play football, but one of them broke a window at Mr Mcwhirter's house. Mr Mcwhirter wouldn't give them their ball back.

    The game got started. Allie sat on a stone nearby. Minutes later it was Jimmy's turn to hit the ball. Unluckily, it fell right into Mr Mcwhirter's yard.

    The boys ran over to Mr Mcwhirter's fence (栅栏). The ball was just out of reach.

    "None of us can fit through the fence." Jimmy said.

    The boys looked glum.

    Suddenly, Jimmy got an idea. "Allie, come over!" he called. "Would you like to get that ball for us?"

    Allie looked at the boys. Then she slipped through the fence, picked up the ball and came back out of the yard.

    "Wow," said Troy. "So quick! Thanks, Allie."

    "Nice job," said Jimmy.

    "Come on," said Ryan, suddenly proud of his kid sister. "I'll teach you how to swing the bat."

Qian Xuesen was born in Hangzhou, Zhejiang Province on December 11, 1911. He left Hangzhou at the age of three when his father obtained a post in Beijing. He graduated from the High School Affiliated to Beijing Normal University and attended Shanghai Jiaotong University. There, he received a degree in mechanical engineering with an emphasis on railroad administration.

After his graduation from Shanghai Jiaotong University in 1934, he travelled across the Pacific Ocean to the United States for further study. There he received his PhD degrees in both aerospace and mathematics. After he graduated, he became a professor as well as a researcher who studied rockets and missile theories.

In 1949, when the news of the birth of the People's Republic of China came to the United States, Qian Xuesen and his wife decided to return to China. In 1950, when they were ready to return home, they were stopped by US officials and sent to prison. With the help of Chinese government and his friends, he finally returned home.

When he returned to China in 1955, our country's space research was almost a blank. In 1956, he set up the first research institute of rockets and missiles. From then on, he was in charge of developing China's missile, rocket and spacecraft research programs. He was a pioneer in these related fields and was honored as "The father of China's missiles". He is the pride of the Chinese people. He made important contributions to the missile and space programs in China.

He passed away on October 31, 2009, at the age of 98, but he is a man who still encourages Chinese youth. His devotion to our country was expressed in his saying. "My career is in China, my success is in China and my destination is in China!" When someone said he could make much more money if he stayed in the United States, he laughed and said, "My family name is Qian, but I don't like qian."

A Chinese film production, Qian Xuesen, directed by Zhang Jianya and starring Chen Kun as Qian Xuesen, was released on December 11, 2011 in both Asia and North America, and on March 2, 2012 in China.