题目

On a Friday night, a poor young artist stood at the gate of the New York railway station, playing his violin. The music was so great that many people stopped to put some money into the hat of the young man. The next day, the young artist came to the same place, and put his hat on the ground gracefully. Different from the day before, he took out a large piece of paper and laid it under his hat. Then he began to play the violin. It sounded more pleasant than ever. Soon he was surrounded with people who were attracted by the words on that paper. It said, “Last night, a gentleman named Ge1．用示意图或图示的方法能够直观形象地将化学知识传授给学生，下列示意图或图示正确的是（　　）A．砷原子结构示意图B．水分子的电子式C．    酸碱中和滴定D．    生产原料甲醛与氨的    物质的量之比为3：2