I do not know whether you realize it, but this condition is essential to us.
我不知道你是否了解,但是,这个条件对我们是必要的。
Thus one simple fact, a change in the number of bison, had an effect on the whole wildlife chain of the plains.
因此,出现了这样一个简单的事实--野牛数目换的变化对平原的整个野生生物链都产生了影响。