题目

当桑树等植物的茎被折断时，从茎的断面上会渗出白色的汁液，流出该汁液的结构是（） A . 筛管 B . 导管 C . 髓 D . 形成层 答案：A－How beautiful your dress is !     －_____. [     ]A. I don't think soB. No, it isn't beautifulC. Thank youD. Please .don't say so