题目

Susan started to clean the room；            Lily was preparing lunch．     A．however                  B．but                            C．meanwhile        D．when 答案：C秋水仙素诱导多倍体形成的原因是A．诱导染色体多次复制B．抑制细胞有丝分裂时纺锤体的形成C．促进染色单体分开，形成染色体D．促进细胞融合