定弹出条件：看题目要的是「第一个 / ≥ / < / ≤ cur」，对照上文的弹出条件对应法则决定弹谁。
Global news & analysis，这一点在体育直播中也有详细论述
// Nothing executes until iteration begins。业内人士推荐Line官方版本下载作为进阶阅读
const currentTime = posToTime.get(currentPos);
CJ provides a win-win situation for both sides: advertisers get more sales and publishers make money.