expanding arbor

例句：

1. 1. The tree's expanding arbor is visible from the road.
   从马路上可以看到这棵树正在扩张的树冠。
2. 2. The forest was filled with the sound of birds singing as the branches expanded.
   森林里充满了鸟儿歌唱的声音，因为树枝在扩张。
3. 3.The scientist carefully observed the expanding arbor to study its growth patterns.
   科学家仔细地观察着正在扩张的树枝来研究其生长模式。