题目

It was not until she had arrived home_______ her appointment with the doctor A. did she remember                          B. that she remembered C. when she remembered                       D. had she remembered 答案：B下列关于科学实验及方法的叙述正确的是 [     ]A．科学家利用光学显微镜观察细胞膜时发现其具有暗—亮—暗三层结构B．桑格和尼克森在研究生物膜分子结构时，运用了建构物理模型的方法C．恩格尔曼采用了同位素示踪法发现了光合作用的部位D．用甲基绿和吡罗红混合液对DNA和RNA染色后的细胞是活细胞