1. 引起：a hard nut to crack 棘手的问题 . | give occasion to 引起 . | on occasion 间或,有时 .
2. 引起; 使发生：for the occasion 临时 | give occasion to 引起; 使发生 | have no occasion for 没有...的根据; 没有必要
1. People know exactly what to give on what occasion, and how much the gift should cost.