By now, most people have heard of bitcoin. Bitcoin is a virtual currency that has had a huge rise in value during 2017. Bitcoin however is just one of many cryptocurrencies. A cryptocurrency is a kind of money that does not exist in the form of bills

发表于:2019-01-03 / 阅读(54) / 评论(0) 分类 2018年VOA慢速英语(一)月