题目

Imagine using your coat to look through the internet, send and receive messages, and even read a map. Yes, you read that correctly—your coat. It may sound silly, but it’s something scientists are working on. Researchers at Shanghai’s Fudan University have made a new type of cloth that can be used as a digital display （显示屏）. Professor Peng Huisheng and his team have spent 10 years trying to make “digital cloth”. After testing different combinations, they chose two materials that worked: a silver-plated yarn （镀银纱）that can light up and a kind of thread （纺线）th 将人红细胞置于盛有下列液体的离心管中。10分钟后离心，得到沉淀物和上清液，则上清液中K+含量最高的离心管内盛有［注：K+主要存在于细胞内］ [　　] A．10％氯化钠溶液 B．0.9％氯化钠溶液 C．20％蔗糖溶液 D．蒸馏水