中文摘要：

根据设定的保质期确定买赠策略进行促销，已经成为易腐品零售商通常采用的管理策略。通过区分潜在需求和实际需求，分析了零售商的策略选择问题，构建了数学模型以确定缺货时间并最大化零售商总利润。结果表明，根据不同参数，零售商可能选择混合策略、完全买赠策略或缺货策略，并得出不同策略在实践中的关注焦点。采用数值算例和灵敏度分析，说明了策略实施的效果以及在实践中的应用情境，由此说明模型有效性和相关管理启示。

英文摘要：

Extra-product promotion policies in line with products＇ expiration date have been widely adopted by the retailer to manage operating decisions for deteriorating items. After distinguishing between underlying demand and realized demand, the retailer＇ s ordering and promotion decision problem was established. The objective is to determine the optimal ordering quantity and shortage time to maximize the total profit during the shelf-life of the deteriorating item. Theoretical results reveal that the retailer would choose one of the three policies, mixed policy, extra-product policy and shortage policy, based on specific parameters. Furthermore, the key points to implement different policies into the practice were obtained. Numerical examples and sensitive analysis were conducted to explain effects and applications of different policies, which illustrate the effectiveness of the model and relevant managerial insights simultaneously.