52.The relative motion of the plates carrying these continents has been constructed in detail, but the motion of the plates with respect to another cannot readily be translated into motion with respect to the earth's interior.

　　53.Wearing a seat belt saves lives; it reduces your chance of death or serious injury by more than half.

　　54.While warnings are often appropriate and necessary——the dangers of drug interactions, for example——and many are required by state or federal regulations, it isn't clear that they actually protect the manufacturers and sellers from liability if a customer is injured.

　　55.At the same time, the American Law Institute——a group of judges, lawyers, and academics whose recommendations carry substantial weight——issued new guidelines for tort law stating that companies need not warn customers of obvious dangers or bombard them with a lengthy list of possible ones.

　　56.In the past year, however, software companies have developed tools that allow companies to push information directly out to consumers, transmitting marketing messages directly to targeted customers.

　　57.The examples of Virtual Vineyards, Amazon.com, and other pioneers show that a Web site selling the right kind of products with the right mix of interactivity, hospitality, and security will attract online customers.

　　58.An invisible border divides those arguing for computers in the classroom on the behalf of students'career prospects and those arguing for computers in the classroom for broader reasons of radical education reform.

　　59.Rather, we have a certain conception of the American citizen, a character who is incomplete if he cannot competently access how his livelihood and happiness are affected by things outside of himself.

　　60.Besides, this is unlikely to produce the needed number of every kind of professional in a country as large as ours and where the economy is spread over so many states and involves so many international corporations.

　　61.But, for a small group of students, professional training might be the way to go since well-developed skills, all other factors being equal, can be the difference between having a job and not.

　　62.Declaring that he was opposed to using this unusual animal husbandry technique to clone humans, he ordered that federal funds not be used for such an experiment-although no one had proposed to do so——and asked an independent panel of experts chaired by Princeton President Harold Shapiro to report back to the White House in 90 days with recommendations for a national policy on human cloning.

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