M buys free-coffee coupons from people who are awarded the coupons. The coupons are sold to people who pay less for the coupons than they would pay by purchasing directly. This marketing of coupons results in lost revenue for UN. To discourage such transactions, A. 找M可能也要做飞机 B. 坐船也有成功的 C. 科学家正加紧研制网络starbuck's D. 最好大家一起starbuck's