A、Reading textbooks. B、Appreciating photos. C、Meeting the boss. D、Using cell phone. D短文中提到，人们在用餐时不断用手机给朋友发送信息、浏览网页或给老板发邮件，故答案为D)

Cell phone has become part of the restaurant table setting besides knife, fork and napkin.
     (19)Distracted dining is the new norm with customers constantly texting friends, surfing the Internet, sending a photo of the meal they’re about to chow down or emailing the boss. For many smart-phone users, it’s hard just to focus on the meal and company at hand.
     (20)Now, one restaurant in Los Angeles is giving diners a reason to turn off the digital world. It will offer customers a 5-percent discount on their bill if they are willing to check their phones at the door. The restaurant is located on Beverly Boulevard. It hopes this gives customers a way to truly sit back and relax, enjoy their meal and actually talk with friends and family in person.
    The owner of the restaurant explains that it’s really not about people disrupting other guests. But because the restaurant is home, and wants to create the atmosphere of home. It’s about two people sitting together and just connecting, without the distraction of a phone. The owner tries to create a place where you come in and really enjoy the experience and the food and the company.
    Some customers say that the suggestion reminds them to keep cell phone usage outside the restaurant. Whenever they go into the restaurant, on every table, there are wine glasses, silverwares and delicious meals.(21)At first, they are not quite used to it. But later, it becomes a trend to go to the restaurant to enjoy a quiet period without the phone at hand. They also enjoy the discount offered by the considerate owners of the restaurant.
19. What commonly distracts customers from their meals and company?
20. What is the restaurant in Los Angeles doing?
21. What are some customers’ attitudes to the offer?