Because these algorithms process the input sequence backward, they requre bidirectional iterators. 因为这些算法向后处理输入序列，所以它们要求双向迭代器。
Bed regeneration and subsequent treatment of the concentrated regenerant are an integral part of the overall treatment process. 床层的再生和浓缩再生剂的后处理都是整个处理过程不可分割的一部分。
