题目

   There are some new drivers going back to school. Teens who have recently gotten their driver's licenses may be taking the wheel to drive to school this fall. However, parents fear when their teen starts driving. And it turns out that such parental fears are justified — so it's worth reviewing how to keep your teen safe while he or she is behind the wheel.    Motor vehicle crashes are the leading cause of death in U. S. teens. Drivers 16 to 19 years old are at the greatest risk for crashes. In fact, their risk is 4 times greater than for older drivers. The teens at the greatest中科院动物所和福州大熊猫研究中心合作，通过将大熊猫的细胞核植入去核后的兔子卵细胞中，在世界上最早克隆出一批大熊猫早期胚胎，这表明我国的大熊猫人工繁殖研究再次走在世界前列。下列有关克隆大熊猫胚胎的叙述中，错误的是 A．在形成早期胚胎的过程中，依次经历了卵裂、桑椹胚、囊胚、原肠胚等几个阶段 B．兔子卵细胞质的作用是激发大熊猫细胞核的全能性 C．克隆出的早期胚胎中，各细胞间具有相同的遗传信息 D．在形成早期胚胎的过程中，尚未出现细胞的分化