题目

— How much ______ the trousers?— ________ twenty dollars. A . is; It's B . are; It's C . are; They're D . is; They're 答案：C下图为植物的几种组织，组成它们的细胞在形态、结构和功能上有很大差异。你认为与这一现象有关的生理活动是A．细胞分化 B．细胞生长 C．细胞分裂 D．细胞成熟