腰身

例句：

1. 1. She sat down on the couch with her back against the wall.
   她坐在沙发上，背靠着墙。
2. 2. The doctor advised him to exercise regularly to maintain his good health.
   医生建议他定期锻炼以保持健康。
3. 3. He stood up and stretched his back, feeling relieved after a long day's work.
   他站起来伸了伸背，感觉工作了一整天后轻松多了。