价格歧视需要有将顾客分类的能力和防止套利的能力。解释下列项目是怎样起价格歧视的作用的，并讨

(1)至少一个周六晚上不能在家过夜的旅客才可以购买特价机票。

(2)坚持将水泥送货上门，并以购买者的住址为定价基础。

(3)销售食品加工机时附送10美元折扣的优惠券。

(4)对卫生纸提供临时促销价。

(5)给高收入病人做整形外科手术的要价高于低收入病人。

Price discrimination requires the ability to sort customers and the ability to prevent arbitrage. Explain how the following can function as price discrimination schemes and discuss both sorting and arbitrage:

a. Requiring airline travelers to spend at least one Saturday might away from home to qualify for a low fare.

b. Insisting on delivering cement to buyers, and basing prices on buyers' locations.

c. Selling food processors along with coupons that can be sent to the manufacturer to obtain a S 10 rebate.

d. Offering temporary price cuts on bathroom tissue.

e. Charging high-income patients more than low-income patients for plastic surgery.