题目

在”观察DNA和RNA在细胞中分布”的实验中，下列说法正确的是（ ） A . 染色时先用甲基绿染液，再用吡罗红染液 B . 用8%的盐酸目的之一是使DNA与蛋白质分离，使DNA水解 C . 酒精灯烘干载玻片，可迅速杀死细胞，防止细胞死亡时溶酶体对核酸的破坏 D . 用高倍显微镜可以比较清楚地看到呈绿色的染色体和呈红色的RNA分子—This returned Chinese scholar has become one of the top experts in this field . 　 —Yes , I know him very well . He 　　　 in Africa with wild animals for eight years . 　 A．has worked B．had worked C．worked 　　 D．has been working