阅读下面材料，然后从各题所给的四个选项中选出一个最佳答案。 
Mr. Hamel picked up a grammar book and read us our lesson. I was surprised at how well I understood it－everything he said seemed so easy! Mr. Hamel had never explained things so patiently. It was as if the poor man wanted to give us all his knowledge in one go.
After grammar, we moved on to writing. For this last day, Mr. Hamel had prepared new examples written in a beautiful style: France, Alsace. Everyone worked hard in dead silence. The only sound was the scratching of pens on paper.
Pigeons (鸽子) cooed softly on the roof. I wondered if they would be forced to sing in
German, too. Mr. Hamel looked at the things around him as if he wanted to remember everything in the small classroom. He had been in this same place for forty years. The desks and chairs were worn with use. The walnut trees in the garden had grown up. The flowers he had planted were now climbing up to the roof.
It must have been sad for the poor man to leave all these things behind. His sister was packing their bags upstairs. They were leaving the country tomorrow.
Mr. Hamel bravely kept on teaching the lesson to the end. After writing, we had history. And at the end of the day, the little children read "BA, BE, BI, BO, BU" together. The old man put on his glasses and read with them. He held his textbook tightly in both hands. His voice was shaking.
Suddenly, the church bell rang. Mr. Hamel got up from his chair. His face was pale, but he had never looked so tall before.
"My friends, I…" But something stopped him. He could only turn around and pick up a piece of chalk. As large as he could, he wrote "…"
"Today's lesson is over. You can go now," he said.
