闰秒

例句：

1. 1. The clock was set for the extra second that occurred during the leap year.
   时钟被设定为闰年出现的额外一秒。
2. 2. The scientist explained how a leap second could affect global timekeeping systems.
   科学家解释了如何一个闰秒会影响全球的时间计量系统。
3. 3. The extra second added to the total time difference between two events.
   额外的一秒增加了两个事件之间的总时间差。