题目

阅读理解Japan's biggest airline is betting that the future of travel isn't traveling at all. For the last month, a married couple has been interacting with a robot—called an Avatar—that's controlled by their daughter hundreds of miles away. Made by ANA Holdings Inc. , it looks like a vacuum cleaner with an iPad attached. But the screen displays the daughter's face as they chat, and its wheels let her move about the house as though she's really there.Virtual travel is nothing new, of course. Storytellers, travel writers and artists have been stimulating the senses of armchair tourists f一条长为的丝线穿着两个质量均为的金属环A和B，将线的两端都系于同一点O（下图），当金属环带电后，由于静电斥力使丝线构成一等边三角形，此时两环处于同一水平面上，如不计环与丝线的摩擦，两环各带多少电量？