题目

― Sorry, Ann. I’m afraid that I can’t go to the magic show by David Copperfield with you.― ______. No one knows when he will be back here again.A. It doesn’t matter                                        B. Don’t say soC. What a great pity!                                        D. Take it easy 答案：C秋天树叶都变黄了，这是由于细胞中存在花青素的缘故，那么，花青素这种物质存在于哪种结构中（ ）A. 叶绿体B. 细胞壁C. 液泡D. 细胞质