s

例句：

1. 1. I need a single sheet of paper for my report.
   我需要一个单张纸来写我的报告。
2. 2. She is a single woman in her thirties.
   她是一个三十多岁的单身女性。
3. 3. The book is on the shelf, and there are only two books left.
   这本书在书架上，只剩下两本书了。