ungraded stream

例句：

1. 1.The ungraded stream is a popular destination for hikers and swimmers.
   这条无分级的河流是徒步者和游泳者的一个热门目的地。
2. 2. The ungraded stream runs through the forest, providing a natural habitat for wildlife.
   这条无分级的河流穿过森林，为野生动物提供了自然栖息地。
3. 3.The ungraded stream is a symbol of the natural beauty of our region.
   这条无分级的河流是我们地区自然美景的象征。