Questions下列各are based on the following passage. Someday a stranger will read your e-mail without your permission or scan the Websites youve visited. Orperhaps someone will casually glance through your credit card purchases or cell phone bills to find out yourshopping preferences or calling habits. In fact, its likely some of these things have already happened to you. Who would watch you without yourpermission? It might be a spouse, a girlfriend, a marketing company, a boss, a cop or a criminal. Whoever it is, theywill see you in a way you never intended to be seen--the 21st century equivalent of being caught naked. Psychologists tell us boundaries are healthy, that its important to reveal yourself to friends, family and loversin 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 somecases, a Google search can reveal what you think. Like it or not, increasingly we live in a world where yousimply 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 foundan overwhelming pessimism 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 fraction of Americans change any behaviors in an effortto 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. Privacyeconomist Alessandro Acquisti has run a series of tests that reveal people will surrender personal information likeSocial Security numbers just to get their hands on a pitiful 50-cents-offcoupon(优惠劵). But privacy does matter--at least sometimes. Its like health: When you have it, you dont notice it. Only when its gone do you wish youd done more to protect it. What does the author mean by saying 'the 21 st century equivalent of being caught naked' (Line 3, Para.2 )?