// i表示当前要插入的元素索引（从第2个元素开始）
咱们结合上面的例子，看看底层发生了什么。
。关于这个话题，Line官方版本下载提供了深入分析
England face off against New Zealand in their final game before the semi finals. England have already secured their spot in the semi finals, but New Zealand need a result. The pressure is all on the Black Caps.
{\renewcommand{\arraystretch}{1.5}\begin{bmatrix}