题目

 现有10个数，其平均数是4，且这10个数的平方和是200，那么这10个数的标准差是（      ） A.1             B.2            C.3            D.4  答案：B Honesty may well be the policy, but it often deserts us when no one is watching, psychologists report today. Experiments with an honesty box to collect payments for hot drinks show that people are better at paying up when under the gaze(注视) of a pair of eyes. The surprise was that the eyes were not real, but photographed.Researchers at Newcastle University set up the experiment in secret. They attached a poster to a cupboard of mugs above an-honesty box alongside a kettle ,with tea, coffee and milk. Over 10 weeks, they alternated each week between images of eyes and pictures of flowers.Dr. Bateson, a behavioral biologist and leader of the study, said that even though the eyes were not real they still seemed to make people behave more honestly. They effect may arise from behavioral characteristics that developed as early humans formed social groups that increased their chances of survival. Individuals had to co-operate for the good of the group, rather than act selfishly."If nobody is watching us, it is in our interests to behave selfishly. But when we think we're being watched,we should behave better, so people see us as co-operative and behave the same way towards us, "Dr. Bateson said."We thought we'd get a slight effect with eyes, but it was quite striking how much difference they made. Even at a subconscious(潜意识的) level, it seems people respond to eyes, and that might be because eyes send a strong biological signal we have evolved(进化) to respond to."The finding, which researchers believe sheds light on our evolutionary past, could be turned to practical use. The psychologists say images of eyes could promote ticket sales on public transport and improve monitor systems to prevent antisocial behavior.1.This passage is mainly about _______________.A.the policy of honestyB.an honesty box to collect moneyC.evolution on honestyD.an experiment on honesty2.The reason for doing the experiment secretly is that the researchers _____________.A.wanted to get a comparatively more exact resultB.had known they wanted to do something illegallyC.meant to get the co-operation of their colleaguesD.intended to sell the hot drinks at a higher price3.People behave honestly under watchful gaze of eyes because _____________.A.they want to leave a good impressionB.they fear to be laughed at by othersC.they've got the nature through evolutionD.they take the photo for a real pair of eyes4.The underlined phrase" sheds light on" in the last paragraph means _____.A.causes somebody to become cheerfulB.makes something easier to understandC.comes upon something by accidentD.brings something into the broad daylight