拿著肯德基的優惠券，可以去吃麥當勞嗎？如果在以前，你一定以為這只是一個玩笑。但是近日，麥當勞的官方網站赫然打出“在麥當勞 別家雞翅優惠券也能用”的廣告。這種“券券通吃”的做法，打響了中國洋快餐界的又一輪促銷大戰。請看《中國日報》的報道：

McDonald's on Wednesday allowed coupons issued by its competitors to be used on its McWings or fried chicken wings, stepping up the fierce competition in the country's fast-food industry.

—— Excerpt from McDonald's to accept rivals' coupons in food fight

優惠券可以翻譯為“coupon”或者“voucher”，持有優惠券的人在購買商品或享受服務時可以抵用一部分（或全部）貨款。根據應用的領域不同，優惠券可以分為購房優惠券（housing voucher）、旅游優惠券（travel voucher）等；電子優惠券（electronic coupon）是優惠券的電子形式。商家推出優惠券是為了刺激銷售（stimulate sales）。

例句：

The Organizing Committee said it was confident the vouchers would stimulate sales. The director said that if 5,000 sets of housing vouchers were used, they would generate 4 billion yuan in housing sales.

—— Excerpt from Housing vouchers stir controversy in Nanjing

The tourism authorities hope to attract more overseas visitors by offering travel vouchers to Citibank's credit card customers who have previous consumption records in the Chinese mainland.

—— Excerpt from Shanghai to issue travel coupons to overseas consumers

類似的促銷手段還有發放打折卡（discount card）等等。例如：

South Beauty, an upscale Chinese restaurant group, this month introduced a 32 percent discount card for customers dining on weekends and holidays.

"With the economy weakening, many companies are tightening their belts in their entertainment budgets," a South Beauty spokeswoman says. "We're trying to retain as many customers as possible by offering the card."

—— Excerpt from More window shoppers than buyers