Add and Remove operations are typically expensive since Binary Search Trees require that a tree be balanced.
添加和删除操作的开销是很大的，只主要是因为对半查找树的平衡性所决定的。
2
It is a shame that the fourth tree is almost clipped off, and there is just a little too much space to the left which, because of the clipped tree, isn't balanced on the right.
很遗憾第四棵树几乎要被剪掉，照片左侧似乎留空过多，因为那课未入镜的树使得右侧也不那么平衡。
3
ReiserFS uses a specially optimized b* balancedtree (one per filesystem) to organize all filesystem data.