无靠背的

例句：

1. 1. The chair was very uncomfortable without a backrest.
   椅子没有靠背非常不舒服。
2. 2. The old tree had no trunk, leaving it vulnerable to the elements.
   这棵老树没有树干，容易受到环境的影响。
3. 3.Without support, the project could not proceed smoothly.
   没有支持，项目无法顺利进行。