1. Based on some relevant facts about the prolongations of a valuation on a module, this paper obtains two necessary and sufficient conditions for a valuation on a module to have a prolongation.
基于一些有关模上赋值的拓展的事实，模上赋值在扩模上存在拓展的两个充分必要条件被获得。
prolongations的翻译
2. The depths in prolongations of dental crown group were much less than those in gingivectomy group when measured postoperatively and six months after operation.
而术后及6个月复查时，牙冠延长术组的龈袋深度均明显低于牙龈切除术组。