One day, Miss Ellis gave her pupils a new kind of homework: homework on happiness. Her pupils would be "happiness1", and were to see what would happen when they tried to bring happiness to those around them. As part of their homework, all the students did really 2, wonderful things, but what Carla Chalmers did left everyone 3 Several days after the homework had been handed out, Carla turned up carrying a big bag.
"Here in this bag I have all the happiness I've collected so far," she said 4 On seeing this, everyone was filled with 5, but Carla didn't want to show anyone what was in the bag. Instead, she pulled out a small box and gave it to her teacher. When Miss Ellis had taken the box, Carla took a(n) 6 camera out of her own pocket and stood with it at the ready.
"Open it, Miss Ellis."
The teacher slowly opened the box and looked inside. A big smile 7 on her face, and at that moment Carla took a photo, Carla's photo came out of the camera immediately, and she 8 it to Miss Ellis along with a sheet of paper. The teacher read the paper in silence, and when she, had finished, she gestured at the 9
"Oh, so it's…"
"Yes!" 10 Carla, opening the bag. "It's a great big pile of smiles!"
She opened the bag and photos of different 11 fell out.
The rest of the class tried to 12 how Carla had managed to create such a great big chain of happiness. All there in the box was a photo of a big smile. But everyone who had seen it felt happiness being transmitted（传送）to them, and in return, without 13, every person 14 with a smile of their own.
She managed to 15 understanding of the smile truth that every time you smile you are sending a gift to the world.
