题目内容：

Life is not easy, so I’d like to say “When anything happens, believe in yourself.”

When I was a young boy, I was too shy to talk to anyone.My classmates often laughed at me.I was sad but could do nothing.Later, something happened, and it changed my life.It was an English speech contest.My mother asked me to take part in.What a terrible idea! It meant I had to speak before all the teachers and students of my school!

“Come on, boy.Believe in yourself.You are sure to win.” Then my mother and I talked about many difficult topics.At last I chose the topic “Believe in yourself”.I tried my best to remember all the speech and practiced it over 100 times.With my mother’s great love and encouragement(鼓励), I did well in the contest.I could hardly believe my ears when the news came that I had won the first place.I heard the cheers from the teachers and students.Those classmates who once looked down on (瞧不起) me now all said “Congratulations!” to me.My mother hugged me and cried excitedly.

Since then, everything has changed for me.When I do anything, I try to tell myself to be confident and I will do a great job.This is true not only for a person but also for a country.

根据短文内容，回答下列问题。

1.Why did the writer’s classmates laugh at him?

2.What could he do when others laughed at him?

3.What changed him and his life?

4.What was the result of the English speech contest?

5.Which sentence do you think is the topic sentence in this passage?