Someday a stranger will read your e-mail without your permission or scan the Website you've visited，Or perhaps someone will casually glance through your credit card purchases or cell phone bills to find out your shopping preferences or calling habits. In fact, it's likely that some of these things have already happened to you. Who would watch you without your permission? It might be a spouse, a girl friend, a marketing company, a boss, a cop or a criminal. Whoever it is, they will see you in a way you never intended to be seen ---- the 21st century replacement of being caught naked. Psychologists tell us boundaries are healthy, that it's important to reveal yourself to friends, family and lovers in stages, at appropriate times. But few boundaries remain. The digital bread crumbs(碎屑) you leave everywhere make it easy for strangers to reconstruct who you are, where you are and what you like. In some cases, a Google search can reveal what you think. Like it or not, increasingly we live in a world where you simply cannot keep a secret. The key question is: Does that matter? For many Americans, the answer apparently is 'no.' When opinion polls ask Americans about privacy, most say they are concerned about losing it. A survey found a strong bad feeling about privacy, with 60 percent of respondents saying they feel their privacy is 'slipping away, and that bothers me.' But people say one thing and do another. Only a tiny part of Americans change any behaviors in an effort to preserve their privacy. Few people turn down a discount at tollbooths(收费站) to avoid using the EZ-Pass system that can track automobile movements. And few turn down supermarket loyalty cards. Privacy economist Alessandro Acquisti has run a series of tests that reveal people will give away personal information like Social Security numbers just to get their hands on a pitiful 50-cents-off coupon(优惠卷)。 But privacy does matter ---- at least sometimes. It's like health: When you have it, you don't notice it. Only when it's gone do you wish you'd done more to protect it. 51. What does the author mean by saying 'the 21st century replacement of being caught naked'? A. People's personal information is easily accessed without their knowledge. B. In the 21st century people try every means to look into others' secrets. C. People tend to be more frank with each other in the information age. D. Criminals are easily caught on the spot with advanced technology. 52.What would psychologists advise on the relationships between friends? A. Friends should open their hearts to each other. B. Friends should always be faithful to each other. C. There should be a distance even between friends. D. There should be fewer arguments between friends. 53. Why does the author say 'we live in a world where you simply cannot keep a secret'？ A. Modern society has finally developed into an open society. B. People leave traces around when using modern technology. C. There are always people who are curious about others' affairs. D. Many search engines benefit from giving away people's identities. 54. What do most Americans do as for privacy protection? A. They change behaviors that might disclose their identity. B. They use various loyalty cards for business transactions(交易).. C. They rely most and more on electronic devices. D. They talk a lot but hardly do anything about it. 55. According to the passage, privacy is like health because ___. A. people will make every effort to keep it. B. its importance is rarely understood C. it is something that can easily be lost D. people don't treasure it until they lose it