To become wealthier,a country needs strong growth in productivity-the output of goods or services from given inputs of labor and capital.For most people,In theory at least,higher productivity means the expectation of rising wages and abundant job opportunities Productivity growth in most of the worlds rich countries has been dismal since around 2004.Espe-cially vexing is the sluggish pace of what economists call total factor productivity--the part hat accounts for the contributions of innovation and technology.In a time of facebook smartphones,self-driving cars,and computers that can beat a person at just about any board game,how can the key economic measure of technological progress be so pathetic?Economists have tagged this the productivity paradox Some argue that because today's technologies are not nearly as impressive as we think.The leading proponent of that view,Northwestern University economist Robert Gordon,contends that compared with breakthroughs like indoor plumbing and the electric motor,today's advances are small and of limited economic benefit.Others think productivity is in fact increasing but we simply don't know how to measure things like the value delivered by Google and Facebook,particularly when many of the benefits are‘free.Both views probably misconstrue what is actually going on.It's likely that many new technologies are used to simply replace workers and not to create new tasks and occupations.What's more,the technologies that could have the most impact are not widely used Driverless vehicles,for instance,are still not on most roads.Robots are rather dumb and remain rare outside manufacturing.And AI is mysterious for most companies.What's happening now may be a replay of the late 80s,says Erik Brynjolfsson,another MIT economist.Breakthroughs in machine learning and image recognition are"eye-popping";the delay in implementing them only reflects how much change that will entail."It means swapping in AI and thinking your business,and it might mean whole new business models he says.In this view,AI is what economic historians consider a"general-purpose technology.These are inventions like the steam engine,electricity,and the internal-combustion engine.Eventually they transformed how we lived and worked.Illustrating the potential of AI as a general-purpose technology,Scott Stern of MITs Sloan School of Management describes it as a"method for a new method of invention But he also warns against expecting such a change to show up in macroeconomic measurements anytime soon."If I tell you we're having an innovation explosion,check back with me in 2050 and I'll show you the impacts,Scott Stern says.General-purpose technologies,he adds,"take a lifetime to reorganize around
According to Paragraph 1,productivity refers to
A.the criteria to measure a powerful country
B.the impetus for people to work harder
C.the capacity to produce goods and services
D.the prerequisite for innovation and high-tech

People are,on the whole,poor at considering background information when making individual decisions.At first glance this might seem like a strength that 1 the ability to make judgments which are unbiased by 2 factors.But Dr.Uri Simonsohn speculated that an inability to consider the big 3 was leading decision-makers to be biased by the daily samples of information they were working with.4,he theorised that a judge 5 of appearing too soft 6 crime might be more likely to send someone to prison 7 he had already sentenced five or six other defendants only to probation on that day.To 8 this idea,he turned to the university-admissions process.In theory,the 9 of an applicant should not depend on the few others 10 randomly for interview during the same day,but Dr Simonsohn suspected the truth was 11.He studied the results of 9,323 MBA interviews,12 by 31 admissions officers.The interviewers had 13 applicants on a scale of one to five.This scale 14 numerous factors into consideration.The scores were 15 used in conjunction with an applicant's score on the Graduate Management Admission Test,or GMAT,a standardised exam which is 16 out of 800 points,to make a decision on whether to accept him or her.Dr Simonsohn found if the score of the previous candidate in a daily series of interviewees was 0.75 points or more higher than that of the one 17 that,then the score for the next applicant would 18 by an average of 0.075 points.This might sound small,but to 19 the effects of such a decrease a candidate would need 30 more GMAT points than would otherwise have been 20.
A.fond
B.fearful
C.capable
D.thoughtless

Growing bodies need movement and（ ）,but not just in ways that emphasize competition.
A.care
B.nutrition
C.exercise
D.leisure

Instincts are the natural resources of human behavior,the raw materials of action,feeling,and thought.They are the primary motives and the indispensable instruments of action.But like other natural resources,men's original tendencies must be controlled and redirected,if they are to be frurtfully utilized in the interests of human welfare.There are a number of conditions that make imperative the control of native tendencies.The first of these is intrinsic to the organization of instincts themselves:impulses are stimulated at random and collide with one another.Often one impulse,be it that of curiosity or aggression,can be indulged only at the expense or frustration of many others just as natural,normal,and inevitable.A life is a long-time enterprise and it contains a diversity of desires.If all of these are to receive any measure of fulfillment there must be compromise and adjustment between them;they must all be subjected to some measure of control.A second cause for the control of instinct lies in the fact that people live and have to live together.The close association which is so characteristic of human life is partly attributable to a specific gregarious instinct,partly to the increasing need for cooperation which marks the increasing complexity of civilization.But whatever be its causes,group association makes it necessary that men regulate their impulses and actions with reference to one another.Endowed as human beings are with more or less identical sets of original native desires,the desires of one cannot be freely fulfilled without frequently coming into conflict with the similar desires of others.Still another imperative reason for the control of our instinctive equipment lies in the fact that instincts as such are inadequate to adjust either the individual or the group to contemporary conditions.They were developed in the process of evolution as useful methods for enabling the human animal to cope with a radically different and incomparably simpler environment.While the problems and processes of his life and environment have grown more complex,man's inborn equipment for controlling the world he lives in has,through the long history of civilization,remained practically unchanged.And,finally,so vastly complicated have become the physical and the social machinery of civilized life that it is literally impossible to depend on instincts to adjust us to an environment far different from that to which they were in the process of evolution adapted.In the light of these conditions men have found that if they are to live happily and fruitfully together,certain original tendencies must be stimulated and developed,others weakened,redirected,and modified,and still others,within limits possibly,altogether repressed.

For months Twitter,the micro-blogging service,has received the kind of free attention of which most companies can only dream.Politicians,corporate bosses,activists and citizens（1）the plat form to catch every tweet of America's new president,who has become the service's（2）"The whole world is watching Twitter,"（3）Jack Dorsey,the company's chief executive,（4）hepresented its results on February 9th.He has little else to brag about.But Donald Trump has not provided the kind of boost the（5）firm really needs.It reported（6）revenue growth and a loss of s 167m.User growth has been sluggish,too:it added just 2musers in that period.Facebook added 72m.The day of the results,shares in Twitter dropped by 12%.（7）news outlets around the world already report（8）Mr Trump,'s most sensational tweets,many do not feel compelled to join the platform to（9）them.Others are（10）by mobs of trolls and large amounts of misinformation And not（11）Mr Trump could change the cold,hard truth about Twitter:that it can never be Facebook.True,it has become one of the most important（12）for public and political（13）among its 319m monthly users.It played an important role in the Arab spring and（14）such as Black Lives Matter.But the platforms freewheeling nature makes it hard to spin gold from.（15）,really trying to do soby packing Twitter feeds（16）advertising,say-would drive away users Twitters latest results are likely to encourage those who think it should never have become a（17）listed company,and want it to consider alternate models of ownership,such as a co-opera-tive.They（18）1Twitter as a kind of public utility-a"people's platform"the management of which should concern public（19）rather more than commercial ones.If the company were coop-eratively owned by users,it would be（20）from short-term pressure to please its investors and meet earnings targets.（10）选？
A.given up
B.taken away
C.put off
D.sent back

Priests,teachers and parents have for generations advised their wards io think twice before speaking,to count to ten when angry and to get a good night's sleep before making big decisions.Social networks care little for seconcl thoughts.Services such as Facebook and Twitter are built to maximise"virality",making it irresistible to share,like and retweet things.They are getting better at it:fully half of the 40 most-retweeted tweets clate from January last year.Starting this month,however,users of WhatsApp,a messaging service owned by Facebook,will find it harder to spread content.They will no longer be able to forward messages to more than 20 0thers in one go,down from more than 100.The goal is not to prevent people from sharing information-only to get users to think about what they are passing on.It Js an idea other platforms should consider copying.Skeptics point out that WhatsApp can afford to hinder the spread of information on its platform because it does not rely on the sale of adverrisements to make money.Slowing down sharing would be more damaging to social networks such as Facebook and Twitter,which make money by keeping users on their sites and showing them ads.Their shareholders would surely refuse anything that lessens engagement.Sure enough,Facebook's shares fell by 23%in after-hours trading,partly because Mark Zuckerberg,its boss,said that its priority would be to get users to interact more with each other,not to promote viral content.Yet the short-term pain caused by a decline in virality may be in the long-term interests of the social networks.Fake news and concerns about cligital addiction,among other things,have already damaged the reputations of tech platforms.Moves to slow sharing could lielp see off harsh action by regulators and lawmakers.They could also improve its service.Instagram,a photo-sharing social network also owned by Facebook,shows that you can be successful without resorting to virality.It offers no sharing options and does not allow links but boasts more than a billion monthly users.It has remained relatively free of misinformation.Facebook does not break out Instagram's revenues,but it is thought to make money.The need to constrain virality is becoming ever more urgent.About half the world uses the internet today.The next 3.8bn users to go online will be poorer and less familiar with media.The examples of deceptions,misinformation and violence in India suggest that the capacity to manipulate people online is even greater when they first gain access to cligital communications.Small changes can have big effects:social networks have become expert at making their services compulsive by adjusting shades of blue and the size of buttons.They have the knowledge and the tools to maximise the sharing of information.That gives them the power to limit its virality,too.
It can be inferred from Paragraphs 4 and 5 that controlling virality could
A.eliminate concerns about digital addiction.
B.keep a social network free of misinformation
C.contribute to the success of a social network.
D.exempt a social network from harsh regulation