题目

—Jean, I didn’t do very well in this test. —____. I’m sure you will make great progress if you improve the way you study. A. Not at all    B. Don’t lose heart  C. I hope so            D. Never mind 答案：B下列过程仅包含物理变化的是A．光合作用 B．干冰升华 C．煤的燃烧 D．金属锈蚀