题目

The father as well as his three children _____ skating on the freezing river every Sunday afternoon in winter.A. is going    B. go    C. goes     D. are going 答案：C下列关于DNA粗提取与鉴定的说法正确的是 A．析出DNA时要缓慢地加蒸馏水，当析出黏稠物时即不再加水 B．在探究洗涤剂对植物细胞DNA提取的影响实验中，自变量是洗涤剂和食盐 C．提取的DNA溶解后加入二苯胺试剂即可染成蓝色 D．将含有DNA的滤液放在60～75℃的恒温水浴箱中保温后过滤，能去除蛋白质杂质