So he keeps on studying after his English classes in order to prepare for life in America.
所以他在英语课下课后还继续学习,为以后在美国生活做准备。
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。