single buoy mooring system

例句：

1. 1.The single mother was struggling to make ends meet.
   这位单身母亲在努力维持生计。
2. 2.He has a single friend in town.
   他在城里只有一个朋友。
3. 3. She is a solitary figure in the crowd.
   她在人群中是孤独的一个。