It's an impenetrable wall of grey. 这堵灰色皮墙围得非常坚固 很难突破

242. This herd contains calves, easier targets.
     这一象群里有更容易下手的幼象
243. But how to reach them?
     但是怎样才能接近呢？
244. The adults encircle their young.
     成年象已经围成圈在保护小象
245. It's an impenetrable wall of grey.
     这堵灰色皮墙围得非常坚固 很难突破
246. A few exhausted stragglers are still arriving.
     还有一些筋疲力竭的落伍的大象赶了过来
247. 0ne of them is alone.
     其中一头落单了
248. But it's too big for the lions to tackle.
     但是由于它的体型太大了 狮子对付不了

来自《行星地球 第一季 第七集 Planet Earth S01E07 伟大草原》第 245 行