题目

下列过程中，细胞遗传物质的结构一定发生改变的是( ) A．细胞分裂      B．细胞分化 C．细胞凋亡                     D．细胞癌变 答案：D(   ) 3. We can't work out the maths problem. Can you tell us        ？   A. how to do   B. what to do it   C. how to do it   D. what should to do