retentionistn.保留者retentionn.保留物；保存；保持(力)；记忆力retention of placenta胎盘滞留retention of meconium胎便滞留retention time control停留时间控制Retention or abolition死刑存废retention period check保存期检查retention time counter保留时间计数器retention of ownership所有权保留retention flocculation延迟絮凝retention and drainage助留助滤retention type catheter留置导尿管； 潴留导尿管