【答案解析】本文介绍了美国人在外就餐时的风俗习惯。
1. D。细节题。根据第一段及关键句 …it is impolite to light up a cigarette without asking if it will disturb them 可知 A、B、C 与原文不相符，同时关键句告诉我们“未经他人允许吸烟是不礼貌的”可知 D 为正确选项。
2. D。细节题。根据 At American restaurants and coffee shops you are usually served tap water before you order 可见在点菜之前提供的是自来水，据此选 D。
3. C。细节题。根据 If you can’t finish your meal but would like to enjoy the food later, ask your waitress or waiter for a “doggie bag” 得知它与答案 C 的表达相符，故选 C。
