题目

    I am Ann, a student from Canada. I was so   36    to be picked to represent Canada on this trip to visit Pompeii and Loulan, both of  37    became lost civilizations about 2,000 years ago.   On the morning of 16th July, we went to a lecture about Pompeii.   38    in the 8th century BC, the city was taken over by the Romans and then became a rich city.   39   , it was destroyed by a volcano, together with all the people in the city. The next day, I was amazed to see the ancient Roman city of Pompeii  40   it was 2,000 years ago. When I walked around the city,将一个土豆（含有过氧化氢酶）切成大小和厚薄相同的若干片，放入盛有一定体积和浓度的过氧化氢溶液的针筒中（如图1所示），若土豆片为4片时，每隔5分钟收集一次数据，根据数据绘制出如图2中曲线1．则曲线2是指改变如图1中何种条件后气体的收集曲线（　　） A、①B、②C、③D、②或③