根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。    

    When I was 13 years old, a boy gave me an important gift. It was a 1. It was the early autumn of my first year at a junior high school and my old school was far away. 2, no one knew who I was. I was very lonely and afraid to make friends with 3.

    Every time I heard the other students talking and laughing. I 4 my heart break. I couldn't talk to anyone about my problems, and I didn't want my parents to 5 me. Then one day, my classmates talked happily with their friends, but I sat at my desk 6 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 7 me and without a word, smiled.

    Suddenly I felt the touch of something bright and friendly. It  8 me feel happily, lively and warm. That smile changed my life. I started to talk with the other students and made friends. Day by day, I became closer to everyone in my class. The boy with the lucky smile 9 my best friend now.

    I believe that the world is what you think it is. If you think you are lonely, you might always be alone. So smile at the world and it will 10.