a sales voucher的用法和样例：
- The shop is having a sale to clear old stock.
- The local dress shop is having a sale.
- The manager decided to launch a sales drive.
- The coach gave a sales talk on exercise in the school assembly.
- The pretty girl on the cover of the book is just a sales gimmick.
- The pretty girl on the cover of the pictorial is just a sales gimmick.