seconds API

例句：

1. 1. I need to finish my work before the deadline.
   我需要在截止日期前完成工作。
2. 2. The clock is ticking away as time is running out.
   时钟滴答作响，时间正在流逝。
3. 3. She counted the seconds until she saw her friend again.
   她数着秒数直到再次见到朋友。