These blades are so tough 这些叶片十分坚硬

196. yet their labours go almost entirely unnoticed.
     但它们的辛苦劳作几乎难以察觉
197. One of the most remarkable is found here
     其中最出色的
198. on the grasslands of South America.
     出现在南美洲草原
199. These blades are so tough
     这些叶片十分坚硬
200. that virtually no large grass eaters can stomach them.
     几乎没有大型食草动物能消化得了
201. Yet they're harvested on an industrial scale...
     然而却被小小的切叶蚁
202. ...by tiny grass cutter ants.
     大规模采集

来自《行星地球 第二季 第五集 Planet Earth S02E05 草原》第 199 行