Giving a more generalized talk about perennials and annuals, for instance, is going to be of much greater interest to these retired senior citizens than discussing plant biochemistry.

• 做一个普及化多年生植物和长寿植物的演讲比做一个植物的生物化学方面的演讲，对那些已退休年老公民来说，显然更有吸引力。