听力原文：

G: Joseph, you have so many old things in your house.

B: I have collected old things over the years.

G: Do you want to sell them?

B: No. I think old things can bring back sweet memories. The toy train I have had since I was three years old is my favorite. It often makes me think of my happy childhood.

G: How long have you had the model plane over there?

B: I’ve had it for 8 years. I have loved science since I had it.

G: I wish that you’ll have a bigger collection. 

B: Thanks.

Question: Why has Joseph collected old things over the years?

参考答案：

Because he thinks old things can bring back sweet memories.