- A series of stalls with interconnected doors that open simultaneously at the beginning of a race.起跑门：内部有相关门的一系列栅栏，在赛跑开始时同时打开
- A movable barrier that starts an automatic timer when pushed aside by a competitor, such as a skier.活动门：当被竞赛者，如滑雪运动员推开时则启动自动计时器的活动门