2018年7月29日
Sandglass
摘要： We have a sandglass consisting of two bulbs, bulb A and bulb B. These bulbs contain some amount of sand. When we put the sandglass, either bulb A or B 阅读全文
posted @ 2018-07-29 18:52 oc_co 阅读(178) 评论(0) 推荐(1)