拿着肯德基的优惠券，可以去吃麦当劳吗？如果在以前，你一定以为这只是一个玩笑。但是近日，麦当劳的官方网站赫然打出“在麦当劳 别家鸡翅优惠券也能用”的广告。这种“券券通吃”的做法，打响了中国洋快餐界的又一轮促销大战。请看《中国日报》的报道：

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

优惠券可以翻译为“coupon”或者“voucher”，持有优惠券的人在购买商品或享受服务时可以抵用一部分（或全部）货款。根据应用的领域不同，优惠券可以分为购房优惠券（housing voucher）、旅游优惠券（travel voucher）等；电子优惠券（electronic coupon）是优惠券的电子形式。商家推出优惠券是为了刺激销售（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

类似的促销手段还有发放打折卡（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