by how easy it is to approach them. 很轻易便能接近黑猩猩

322. they find a person.
     都能遇见人类
323. Chimps are normally tricky to film in the wild.
     黑猩猩通常很难在野外拍摄
324. But in this human world, the crew are surprised
     但在这里 摄制组惊讶的发现
325. by how easy it is to approach them.
     很轻易便能接近黑猩猩
326. Another one coming up the path.
     另一只沿路过来
327. But back in the forest,
     但在森林里
328. it's a different story.
     情况就不一样了

来自《行星地球 第三季 第五集 Planet Earth S03E05 森林》第 325 行