• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    On the Future: A Keynote Address

    2020-05-22 08:01:50MartinJohnRees
    Engineering 2020年2期

    Martin John Rees

    Member of Order of Merit; Fellow of Royal Society; Fellow of Royal Academy of Engineering; Fellow of United Kingdom Academy of Medical Sciences;Fellow of the British Academy.

    Editor’s note: The following commentary is based on the keynote speech Professor Lord Martin Rees, the United Kingdom’s Astronomer Royal, presented at Engineering in an Unpredictable World: The Global Grand Challenges Summit 2019 in London on 18 September 2019. This and other talks at the Summit are available to watch at:https://www.raeng.org.uk/policy/partnerships/international-policy-and-development/ggcs/2019/welcome/on-demand-2. Based at the University of Cambridge, Lord Rees is a cosmologist and astrophysicist,a philosopher of science,and a former President of the Royal Society.Besides his countless scientific papers,Lord Rees has written a wide range of books, from academic texts to best-selling popular science. The content of Lord Rees’s speech was drawn from his most recent book, On the Future: Prospects for Humanity, published in 2018 [1]. A Chinese translation of the book will be available in 2020.

    People who hear that I have the title ‘‘Astronomer Royal” have been known to ask me:‘‘Do you do the Queen’s horoscopes?”I tell them I am an astronomer, not an astrologer. Scientists are rotten forecasters, almost as bad as economists. So, my predictions of the future are necessarily tentative,and are balanced between scientific optimism and political pessimism.

    My central theme is that although our Earth has existed for 45 million centuries,this century is special.It is the first in which one species has the planet’s future in its hands. We are deep in the Anthropocene,and I shall give you a tour of its technological front lines.

    But I shall focus first on two things we can predict even with a cloudy crystal ball:the world in 2050 will be more crowded,and it will be warmer. Fifty years ago, the population was about 3.5 billion. It is now about 7.7 billion, with the growth mainly in Asia and Africa. Globally, the number of births per year peaked in 2012, and birthrates are now dropping in most countries [2]. But the world population could still rise to about 10 billion by 2050,in part because the majority of people in the developing world are young,have not yet borne children,and are likely to live longer than the generation before them (Fig. 1) [3].

    Despite grim forecasts to the contrary in the 1960s, food production has kept pace with the rising population. Famines still occur, but they are due to conflict or maldistribution, not overall scarcity. As Gandhi observed, there is enough for everyone’s need,but not for everyone’s greed. Feeding ten billion people in 2050 will require further-improved agriculture, including genetically modified crops. Dietary innovations may also play a role, such as artificial meat or converting nutritious insects into palatable food.

    Population levels beyond 2050 are uncertain. Falling infant mortality, urbanization, and improved education for females all foster a demographic transition toward lower birth rates.But there could be countervailing cultural influences. If families in Africa remain large,the UN predicts that the continent’s population could double again between 2050 and 2100,to four billion,thereby raising the global population to 11 billion [4]. Nigeria alone would by then have a population comparable to those of Europe and North America combined. Wealthy nations, especially those in Europe,should urgently promote the growth of prosperity in Africa, and not purely for altruistic reasons.

    The geopolitical stresses ahead are worrying. Those in poor countries now know, largely courtesy of the Internet, what they are missing, and migration is generally easier. This is a recipe for disaffection and instability—multiple mega-versions of the tragic refugee ‘‘boat people” crossing the Mediterranean today, with many dying in the process [5].

    If humanity’s growing numbers continue to impact land use,and if global temperatures rise unabated, the resultant shock to the ecosphere means that we could be destroying the book of life before having the chance to read it.We have already skewed things enormously: there is now more biomass in chickens and turkeys than in all the world’s wild birds [6], and the combined biomass of humans and livestock is about 20 times that of all wild mammals put together [7]. For many environmentalists, preserving the richness of our biosphere has value in its own right, but it is also an undeniably crucial component of human wellbeing. To quote the great ecologist E. O. Wilson: ‘‘Mass extinction is the sin that future generations will least forgive us for.”

    Feeling the heat

    Here’s a second firm prediction:it will get warmer(Fig.2)[8].In contrast to population issues, climate change is not underdiscussed, but it is certainly under-responded-to. The urgent need for action was re-emphasized by the Intergovernmental Panel on Climate Change in a special report published in October 2018 [9].

    The challenge of prioritizing action comes in part from the very nature of economic theory,which heavily discounts the future.As a result, standard economic models essentially ascribe no value to what happens after 2050. Thus, even people who agree that there is a big risk of climate catastrophe a century hence will differ in how urgently they advocate for action today.Their assessment will depend on expectations of future growth, and optimism about technological fixes. But, to my mind, the urgency of action on climate change depends on an overarching ethical question: should we be optimizing our lives at the expense of future generations?

    Fig. 1. A population of 11 billion people by 2100, predicted by the United Nations’ Population Division, will present an enormous challenge to the planet, and to human ingenuity. Reproduced from Ref. [3], ?2019 United Nations, Department of Economic and Social Affairs, Population Division (CC BY 3.0 IGO).

    Fig. 2. With annual global greenhouse gas emissions still rising, the world will continue to warm, but by how much? The Intergovernmental Panel on Climate Change projects a range of possible outcomes based on a set of potential future emission scenarios—Representative Concentration Pathways (RCP)—increasing from dark blue to red. Vertical bars on the right represent likely ranges for global temperature change for each RCP by the end of the 21st century. Reproduced from Ref. [8], FAQ 12.1, Fig. 1; United Nations, Intergovernmental Panel on Climate Change (CC BY 3.0 IGO).

    As a side note, there is one policy context in which essentially zero discounting is applied:in radioactive waste disposal,depositories are required to prevent leakage for 10 000 years[10].This is ironic,given that we cannot plan energy policy even 30 years ahead.

    But there is one win-win roadmap to a low-carbon future.Nations should accelerate research and development into all forms of low-carbon energy generation, and into other technologies where parallel progress is crucial, such as smart electricity grids and energy storage—batteries, compressed air, pumped storage,flywheels, and so on.

    The faster these cleaner technologies advance, the sooner their prices will fall, making them affordable. This will be especially important to countries such as India, where more generating capacity will be needed, where the health of the poor is jeopardized by smoky stoves burning wood or dung, and where there would otherwise be pressure to build coal-fired power stations.

    Sun and wind energy are front-runners, but other generation methods have geographical niches. For example, tidal energy is attractive where there are especially large-amplitude tides, as on Britain’s west coast. Indeed, there are proposals for tidal barrages or lagoons there.

    Because of the local intermittency of the sun and wind,we will need continental-scale DC grids. These would carry solar energy from the south in Morocco and Spain to the less sunny Northern Europe, and from east to west, in order to smooth peak demand over different time zones in North America and Eurasia, perhaps all the way along the Belt and Road to China.

    And despite ambivalence about nuclear energy, it is surely worthwhile to boost research and development into a variety of‘‘Generation IV” power station concepts, which could prove to be more flexible in size and safer [11]. Furthermore, the potential pay-off from fusion is so great that continuing experiments and building prototypes makes good sense.

    This research and development scenario offers a win-win option for the United Kingdom, too. If the nation hits its legally mandated target of becoming carbon-emissions neutral by 2050[12], global emissions will drop by less than 2%. But we produce about 10% of the world’s best scientific research. By leading in innovation, the United Kingdom can aspire to make far more than 2% difference. It would be hard to think of a more inspiring challenge for young scientists than devising clean and economical energy systems for the world.

    Double-edged swords

    We should be evangelists for new technology—without it, the world cannot provide food and sustainable energy for an expanding,more demanding population.But our future will require wisely directed technology. Indeed, many of us are anxious that technology is advancing too fast for us to cope with it sensibly,and that we have a bumpy ride ahead.

    In healthcare, splendid advances in microbiology—diagnostics,vaccines,and antibiotics—offer prospects of containing pandemics.But these same advances will strengthen concerns about the safety of experiments, the dissemination of ‘‘dangerous knowledge,” and the ethics of how biotechnology is applied. In 2011, for example,research groups in Wisconsin, USA, and the Netherlands showed that it was possible to make the influenza virus both more virulent and more transmissible [13]. To some, this was a frightening portent of things to come.

    The new CRISPR/cas9 technique for gene editing is hugely promising, but there are already ethical concerns, for example,regarding experiments modifying human embryos [14], and anxiety about possible runaway consequences of ‘‘gene drive” programs to wipe out species such as mosquitos or grey squirrels[15].

    Governments will surely adopt a stringent and precautionary attitude to biotechnology. Yet whatever regulations are imposed,they simply cannot be enforced worldwide—any more than drug or tax laws can. Whatever can be done will be done by someone,somewhere.And that is a nightmare.While nuclear bombs cannot be built without huge, conspicuous special-purpose facilities,biotechnology involves small-scale, dual-use equipment. Indeed,biohacking is burgeoning even as a hobby and competitive game[16]. These concerns are relatively near-term—within the next ten or 15 years.It is difficult to even imagine what may be possible in 2050 and beyond.

    Artificial intelligence

    The smartphone, the Internet, and their ancillaries—which are ubiquitous today—would have seemed magical even 25 years ago. So, looking several decades ahead, we must keep our minds open (or at least ajar) to transformative advances that may now seem like science fiction.

    On the biology front, we might expect two things: a better understanding of the combination of genes that determine the key characteristics of humans and animals, and the ability to synthesize genomes that match these features. If it becomes possible to ‘‘play God on a kitchen table,” our ecology—and even our species—may not long survive unscathed.

    And what about another transformative technology: robotics and artificial intelligence (AI)? There have been exciting advances in generalized machine learning. DeepMind’s ‘‘AlphaZero” AI system famously achieved world-championship level in the games of chess, shogi, and Go in a matter of hours (Fig. 3) [17]. AI can already cope better than humans with complex fast-changing networks such as traffic flow or electricity grids. In science, its capacity to explore zillions of options could allow it to discover recipes for better drugs, or perhaps room-temperature superconductors.

    It is,of course,the speed of computers that allows them to succeed:they learn to identify dogs,cats,and human faces by crunching through millions of labeled images—not the way humans learn.Similarly, they learn to translate by reading millions of pages of multilingual text. In Europe, computers are fed European Union documents—their boredom threshold is infinite!

    Fig.3. The ancient Chinese game of Go was yet another bastion of human intellect overcome by artificial intelligence, in the form of DeepMind’s AlphaZero system.(Photo credit: DeepMind, with permission).

    The implications of AI for our society are mixed.If we were sentenced to a term in prison,recommended for surgery,or even given a poor credit rating, we would expect the reasons to be accessible to us and contestable by us. If such decisions were entirely delegated to an algorithm, we would be entitled to feel uneasy, even if presented with compelling evidence that, on average, machines make better decisions than the humans they have usurped.

    AI systems will become more pervasive. Records of all our movements, our health, and our financial transactions will be in the cloud, managed by a multinational quasi-monopoly. The data may be used for benign reasons such as medical research, but its availability to internet companies is already shifting the balance of power from governments to globe-spanning conglomerates.

    Robot revolution

    Clearly, machines will take over much of manufacturing and retail distribution. They can also supplement, if not replace, many white-collar jobs, such as routine legal work, accountancy, computer coding,medical diagnostics,and even surgery.Many professionals will find their hard-earned skills in less demand. In contrast, some skilled service-sector jobs—plumbing and gardening, for example—require non-routine interactions with the external world and will be among the most difficult jobs to automate.

    The digital revolution generates enormous wealth for innovators and global companies. But preserving a healthy society will surely require the redistribution of that wealth.In addition,to create a humane society,governments will need to vastly enhance the number and status of those who care for the old, the young, and the sick. There are currently far too few caregivers, and they are poorly paid, inadequately esteemed, and insecure in their positions.Nevertheless,I would suggest that such employment is more fulfilling than work in call centers or Amazon warehouses, which can be readily automated.

    Be that as it may,society will likely be transformed by the coming wave of robots. If you believe some people, we may even become one with the robots.Leading such enthusiasts is the futurologist Ray Kurzweil. In his book, The Age of Spiritual Machines, he predicted that humans would transcend biology by merging with computers [18]. Kurzweil is worried that his vision may not happen in his lifetime,so he has signed up with a company in Arizona in the United States that, in the event of his untimely death, will freeze and store his body[19].When immortality is finally on offer,this will allow him to be resurrected—or perhaps have his brain downloaded. Personally,I would rather end my days in an English churchyard than an American refrigerator.

    Some insist that ageing is an inconvenient‘‘disease”that can be cured. Or, at least, that human mentality and physique may become malleable thanks to genetic and cyborg technologies.Such secular ‘‘intelligent design” will change us far faster than Darwinian evolution did, and could be a game-changer. When we admire the literature and artefacts that have survived from antiquity, we feel an affinity, across a gulf of thousands of years, with those ancient artists and their civilizations. But we can have zero confidence that the dominant intelligences a few centuries from now will have any emotional resonance with us—even though they may have an algorithmic understanding of how we behaved.

    The final frontier

    And now I turn briefly to another technological arena: space.This is where robots surely have a future,and where I would argue that these changes will happen fastest—and should worry us less.

    We depend every day on space for satellite navigation,environmental monitoring, communications, and more. During this century, the whole solar system will be explored by swarms of miniaturized probes,far more advanced than the probes that have beamed back close-ups of Saturn and its moons, and of Pluto and beyond.

    Think back to the computers and phones of the 1990s, when these now-distant probes were designed, and realize how much better we can do today. The next step will be the deployment in space of robotic fabricators,which can build large structures under zero gravity, such as solar energy collectors or giant telescopes with huge, gossamer-thin mirrors.

    What about crewed spaceflight?The practical case for this gets ever weaker with each advance in robotics and miniaturization. I would argue that private-enterprise ventures like Elon Musk’s Space X should front all crewed missions. Leave it to those courageous thrill-seekers to establish independent bases on Mars, or maybe on asteroids. Musk says he wants to die on Mars, after all—though not on impact [20].

    Just don’t ever expect mass emigration from Earth.Nowhere in our solar system offers an environment even as habitable as the Antarctic or the top of Everest. Here, I disagree with Musk and my late colleague Stephen Hawking. It is a dangerous delusion to think that space offers an escape from Earth’s problems. Dealing with climate change on Earth is a piece of cake compared with terraforming Mars.There is no‘‘Planet B”for ordinary people(Fig.4).

    But those pioneer adventurers who escape the Earth could be cosmically important.This is why:they will be ill-adapted to their new environment,but they will be beyond the clutches of our terrestrial regulators. They will use all the resources of genetics and cyborg technology to adapt. They will change faster and could within a few generations become a new species.

    Back from the future

    Let me conclude by returning to the here and now.My book,On the Future, emphasizes how our interconnected society is brittle and vulnerable. I would argue that we fret unduly about small risks—air crashes, carcinogens in food, low radiation doses—but are in denial about emerging threats that could be globally devastating. Some of these are environmental in nature, including the pressures of a growing, more demanding population, and others are the potential downsides of the novel technologies I have described. In the Anthropocene, a wise mantra might be: ‘‘The unfamiliar is not the same as the improbable.”

    And of course, most of the challenges are global. Coping with potential shortages of food,water and other resources,while transitioning to low-carbon energy, cannot be solved by each nation separately, nor can the regulation of potentially threatening innovations.Indeed,a key issue is whether nations need to give up more sovereignty to new organizations along the lines of the World Health Organization or the International Atomic Energy Agency.

    Fig. 4. There is no ‘‘Planet B” to which humanity can move en masse to escape the growing challenges facing us on our warming Earth, pictured here on 4 September 2019, with a loose chain of tropical cyclones spinning across the Western hemisphere.(Photo credit:NASA Earth Observatory/Joshua Stevens;NOAA National Environmental Satellite, Data, and Information Service).

    Scientists and engineers have an obligation to promote the beneficial applications of their work and warn against the downsides.Universities can use the expertise of their staff,and their convening power, to assess which scary scenarios, eco-threats, or risks from misapplied technology can be dismissed as science fiction, and how best to avoid the serious ones.

    But politicians will not prioritize the global and long-term measures that are needed unless enough voters endorse such policies.So experts must enhance their leverage by involvement with nongovernmental organizations, via blogging and journalism, and by enlisting charismatic individuals and the media to amplify their voice. Pope Francis’s encyclical Laudato si’ [21] had a worldwide influence in the run-up to the Paris climate conference in 2015.There is no gainsaying the Catholic Church’s global reach and concern for the world’s poor.

    And in the United Kingdom in May 2019,I doubt the then-environment secretary Michael Gove would have become exercised about non-degradable plastic waste had it not been for the British Broadcasting Blue Planet II programs, presented by our secular pope, David Attenborough—particularly the images of albatrosses returning to their nests and regurgitating plastic debris for their offspring to eat [22].

    It is encouraging to witness the ranks of activists rising among the young—not least the remarkable Greta Thunberg.This is unsurprising,as today’s young people can hope to live to the end of this critical, special century. Their campaigning is welcome, and their commitment gives me grounds for hope.

    ‘‘Spaceship Earth” is hurtling through the void. Its passengers are anxious and fractious. Their life-support system is vulnerable to disruption and breakdowns. But there is too little planning,too little horizon-scanning. We need to think globally, we need to think rationally, we need to think long-term—empowered by 21st century technology but guided by values that science alone cannot provide.

    Acknowledgements

    Lord Rees would like to thank Sean O’Neill and David Egerter for their assistance in the preparation of this commentary.

    av又黄又爽大尺度在线免费看| 9色porny在线观看| 自拍欧美九色日韩亚洲蝌蚪91| 中文欧美无线码| 精品国产乱码久久久久久小说| 精品一区二区免费观看| 一本色道久久久久久精品综合| 男女国产视频网站| 视频中文字幕在线观看| 少妇猛男粗大的猛烈进出视频| av电影中文网址| 欧美 亚洲 国产 日韩一| 水蜜桃什么品种好| 性色av一级| 午夜精品国产一区二区电影| 亚洲精品一区蜜桃| 日韩欧美一区视频在线观看| 久热这里只有精品99| 99re6热这里在线精品视频| videosex国产| 午夜福利网站1000一区二区三区| 黄片无遮挡物在线观看| 草草在线视频免费看| av又黄又爽大尺度在线免费看| 中国国产av一级| 午夜福利视频精品| 丝袜脚勾引网站| 久久精品夜色国产| 久久久久久人人人人人| 精品一品国产午夜福利视频| 看免费成人av毛片| 人体艺术视频欧美日本| 国产精品 国内视频| 婷婷色综合大香蕉| xxx大片免费视频| 午夜免费鲁丝| 国内精品宾馆在线| 激情视频va一区二区三区| 国产亚洲精品第一综合不卡 | 热99久久久久精品小说推荐| 99国产精品免费福利视频| 国产av码专区亚洲av| 精品国产露脸久久av麻豆| 母亲3免费完整高清在线观看 | 免费av不卡在线播放| 纵有疾风起免费观看全集完整版| 亚洲美女黄色视频免费看| 久久久久久伊人网av| 一级毛片电影观看| 日日爽夜夜爽网站| 亚洲国产最新在线播放| 亚洲欧美一区二区三区国产| 欧美丝袜亚洲另类| 久久精品国产亚洲av天美| 丁香六月天网| 青春草视频在线免费观看| 在线天堂最新版资源| 最近最新中文字幕免费大全7| 亚洲国产最新在线播放| 久久精品熟女亚洲av麻豆精品| 亚洲av日韩在线播放| 免费不卡的大黄色大毛片视频在线观看| 欧美日韩国产mv在线观看视频| 亚洲图色成人| 高清黄色对白视频在线免费看| 国产男人的电影天堂91| 曰老女人黄片| 亚洲欧美成人精品一区二区| 99热国产这里只有精品6| 亚洲精品av麻豆狂野| 蜜桃国产av成人99| 精品视频人人做人人爽| 久久久久久久久久成人| 免费高清在线观看日韩| 这个男人来自地球电影免费观看 | av在线老鸭窝| 人人妻人人爽人人添夜夜欢视频| 免费观看在线日韩| 成人手机av| 亚洲国产av新网站| 国产高清国产精品国产三级| 精品国产国语对白av| 少妇 在线观看| av线在线观看网站| 热99久久久久精品小说推荐| 久久久久久久久久人人人人人人| 边亲边吃奶的免费视频| 亚洲欧美成人综合另类久久久| 欧美国产精品一级二级三级| 18禁在线无遮挡免费观看视频| 水蜜桃什么品种好| 国产乱人偷精品视频| 欧美激情 高清一区二区三区| 中文字幕另类日韩欧美亚洲嫩草| 欧美亚洲 丝袜 人妻 在线| av片东京热男人的天堂| 男女国产视频网站| 性色avwww在线观看| 欧美3d第一页| 巨乳人妻的诱惑在线观看| 国产在线视频一区二区| 欧美精品一区二区大全| 日韩精品有码人妻一区| www.熟女人妻精品国产 | 久久国产精品大桥未久av| av在线观看视频网站免费| 少妇的丰满在线观看| 人人妻人人添人人爽欧美一区卜| 国产精品熟女久久久久浪| 在线亚洲精品国产二区图片欧美| 亚洲丝袜综合中文字幕| 久久女婷五月综合色啪小说| 日本91视频免费播放| 热99久久久久精品小说推荐| 一级毛片黄色毛片免费观看视频| 国产精品一国产av| 亚洲综合色网址| 中文字幕av电影在线播放| 丝袜脚勾引网站| av黄色大香蕉| 国产一区二区三区综合在线观看 | 免费日韩欧美在线观看| 欧美成人精品欧美一级黄| 考比视频在线观看| 精品国产一区二区三区久久久樱花| 国产黄色免费在线视频| 日韩中文字幕视频在线看片| 亚洲色图综合在线观看| 国产精品一区www在线观看| 中文字幕亚洲精品专区| 另类亚洲欧美激情| 免费观看在线日韩| 亚洲美女视频黄频| 中国国产av一级| 中文乱码字字幕精品一区二区三区| 天天躁夜夜躁狠狠躁躁| 欧美激情 高清一区二区三区| 国产熟女欧美一区二区| 如日韩欧美国产精品一区二区三区| 一级片'在线观看视频| 精品卡一卡二卡四卡免费| 蜜桃国产av成人99| 国产精品国产av在线观看| 精品国产一区二区三区久久久樱花| 欧美精品一区二区免费开放| 国国产精品蜜臀av免费| 日日爽夜夜爽网站| 国产精品一二三区在线看| 午夜福利视频在线观看免费| 亚洲国产日韩一区二区| 久久免费观看电影| 在线观看免费日韩欧美大片| 99久久中文字幕三级久久日本| av一本久久久久| 最近手机中文字幕大全| 欧美 日韩 精品 国产| 国产成人一区二区在线| 精品国产一区二区久久| 欧美xxxx性猛交bbbb| 欧美激情 高清一区二区三区| 久久久久精品久久久久真实原创| 日韩免费高清中文字幕av| 精品一品国产午夜福利视频| 亚洲国产av影院在线观看| www日本在线高清视频| 18+在线观看网站| 又大又黄又爽视频免费| 一级黄片播放器| 国产一区二区激情短视频 | 春色校园在线视频观看| 亚洲,欧美精品.| 搡女人真爽免费视频火全软件| 五月天丁香电影| 久久毛片免费看一区二区三区| 中文天堂在线官网| 亚洲av.av天堂| 男男h啪啪无遮挡| 国产欧美日韩一区二区三区在线| 国产精品久久久久久久电影| 91在线精品国自产拍蜜月| 91成人精品电影| 久久免费观看电影| 夜夜骑夜夜射夜夜干| 亚洲欧美成人精品一区二区| 欧美精品一区二区免费开放| 97在线视频观看| 午夜福利视频精品| 狂野欧美激情性bbbbbb| 精品人妻一区二区三区麻豆| av有码第一页| 免费观看a级毛片全部| 青春草亚洲视频在线观看| 黄色视频在线播放观看不卡| 免费少妇av软件| av.在线天堂| 国产成人免费观看mmmm| 毛片一级片免费看久久久久| 午夜精品国产一区二区电影| 不卡视频在线观看欧美| av在线观看视频网站免费| 91久久精品国产一区二区三区| 97人妻天天添夜夜摸| 日韩电影二区| 亚洲av欧美aⅴ国产| 国产欧美另类精品又又久久亚洲欧美| 一级毛片我不卡| 亚洲av在线观看美女高潮| 90打野战视频偷拍视频| 亚洲av成人精品一二三区| 亚洲,一卡二卡三卡| 欧美 日韩 精品 国产| 成年人免费黄色播放视频| 欧美亚洲 丝袜 人妻 在线| 国产精品一区二区在线不卡| 国产黄色视频一区二区在线观看| h视频一区二区三区| 母亲3免费完整高清在线观看 | 免费高清在线观看视频在线观看| 国产亚洲最大av| 久久精品夜色国产| 久久久欧美国产精品| 亚洲精品视频女| 男女国产视频网站| 日韩一区二区三区影片| 宅男免费午夜| 大香蕉久久成人网| 国产成人av激情在线播放| 久久精品久久久久久久性| 人人妻人人爽人人添夜夜欢视频| 亚洲精品,欧美精品| 欧美性感艳星| 成人二区视频| 伦理电影大哥的女人| 日本色播在线视频| 日日爽夜夜爽网站| 内地一区二区视频在线| 亚洲中文av在线| 国产一区二区在线观看日韩| 啦啦啦视频在线资源免费观看| 午夜福利网站1000一区二区三区| 国产一区亚洲一区在线观看| 热99国产精品久久久久久7| 国产免费又黄又爽又色| 人成视频在线观看免费观看| 欧美精品国产亚洲| 亚洲国产精品成人久久小说| 80岁老熟妇乱子伦牲交| 汤姆久久久久久久影院中文字幕| 亚洲国产精品一区三区| 性色av一级| 免费看光身美女| 26uuu在线亚洲综合色| 男男h啪啪无遮挡| 精品亚洲成国产av| 日本-黄色视频高清免费观看| 日韩中文字幕视频在线看片| 成年人午夜在线观看视频| 成年女人在线观看亚洲视频| 免费高清在线观看视频在线观看| 中文字幕最新亚洲高清| 久久久精品区二区三区| 久久精品国产亚洲av涩爱| 69精品国产乱码久久久| 少妇猛男粗大的猛烈进出视频| 国产乱人偷精品视频| 在线天堂最新版资源| www.色视频.com| 一区二区三区乱码不卡18| 欧美精品高潮呻吟av久久| 国产成人精品无人区| av一本久久久久| 久热久热在线精品观看| 国产精品.久久久| 国产成人91sexporn| 国内精品宾馆在线| 秋霞伦理黄片| 久久99蜜桃精品久久| 日日爽夜夜爽网站| 十八禁高潮呻吟视频| 免费观看av网站的网址| √禁漫天堂资源中文www| a级毛色黄片| 亚洲精品美女久久av网站| 少妇人妻久久综合中文| 老司机影院成人| 国产色婷婷99| 日韩一本色道免费dvd| 日韩成人av中文字幕在线观看| av黄色大香蕉| 22中文网久久字幕| 久久午夜综合久久蜜桃| 久久久久久久大尺度免费视频| 国产av精品麻豆| 日韩av免费高清视频| 丰满饥渴人妻一区二区三| 国产欧美亚洲国产| 国产成人91sexporn| 精品一区二区三区视频在线| 亚洲精品一二三| av福利片在线| 一区二区三区乱码不卡18| 日韩欧美一区视频在线观看| 超色免费av| 亚洲色图综合在线观看| 午夜福利视频在线观看免费| 亚洲欧美一区二区三区黑人 | 黄色怎么调成土黄色| 久久精品国产鲁丝片午夜精品| 国产免费福利视频在线观看| 久久ye,这里只有精品| 亚洲国产成人一精品久久久| 熟女电影av网| 一级a做视频免费观看| 国产69精品久久久久777片| 国产成人精品在线电影| 一级毛片电影观看| 国产精品蜜桃在线观看| 最近中文字幕2019免费版| 有码 亚洲区| 超碰97精品在线观看| 大陆偷拍与自拍| 国产精品免费大片| 欧美丝袜亚洲另类| 欧美日韩综合久久久久久| 国产男人的电影天堂91| 亚洲成人一二三区av| 精品国产一区二区三区久久久樱花| 有码 亚洲区| 久久久久久人人人人人| 免费观看在线日韩| 天堂8中文在线网| av在线app专区| 亚洲av欧美aⅴ国产| 美女xxoo啪啪120秒动态图| 自线自在国产av| 亚洲一码二码三码区别大吗| 国产片内射在线| 三上悠亚av全集在线观看| 交换朋友夫妻互换小说| 国产综合精华液| 午夜免费男女啪啪视频观看| 欧美精品av麻豆av| 熟女av电影| 搡老乐熟女国产| 免费少妇av软件| 日韩精品有码人妻一区| 精品一区二区三区视频在线| 久久精品国产亚洲av涩爱| 七月丁香在线播放| 韩国av在线不卡| 欧美日韩综合久久久久久| 久久ye,这里只有精品| 国产乱人偷精品视频| 国产精品成人在线| 亚洲欧美清纯卡通| 免费观看在线日韩| 男人爽女人下面视频在线观看| 免费观看av网站的网址| 亚洲精品日本国产第一区| 狠狠婷婷综合久久久久久88av| 午夜老司机福利剧场| 最近中文字幕2019免费版| 成人无遮挡网站| 久久精品人人爽人人爽视色| 好男人视频免费观看在线| 日韩熟女老妇一区二区性免费视频| 免费观看无遮挡的男女| 免费高清在线观看日韩| 我要看黄色一级片免费的| 熟女电影av网| 欧美国产精品va在线观看不卡| 午夜福利在线观看免费完整高清在| 亚洲欧美清纯卡通| 成人毛片60女人毛片免费| 国语对白做爰xxxⅹ性视频网站| 国产男女超爽视频在线观看| 久久国内精品自在自线图片| 亚洲一码二码三码区别大吗| 久久精品夜色国产| 黄片无遮挡物在线观看| 午夜精品国产一区二区电影| 亚洲av成人精品一二三区| 国产深夜福利视频在线观看| 女人精品久久久久毛片| 日本欧美视频一区| 午夜久久久在线观看| 久久婷婷青草| 成人18禁高潮啪啪吃奶动态图| 尾随美女入室| av国产精品久久久久影院| 在线天堂中文资源库| 一二三四中文在线观看免费高清| 精品国产一区二区三区久久久樱花| 国产在视频线精品| 成人毛片a级毛片在线播放| 亚洲欧美一区二区三区国产| 在线观看免费日韩欧美大片| av在线观看视频网站免费| 激情视频va一区二区三区| 欧美日韩视频精品一区| 高清毛片免费看| 亚洲av.av天堂| 在线观看一区二区三区激情| 日本猛色少妇xxxxx猛交久久| 成人午夜精彩视频在线观看| 欧美日韩视频高清一区二区三区二| 国产一区二区三区综合在线观看 | 国产探花极品一区二区| 91精品伊人久久大香线蕉| 国产免费现黄频在线看| 欧美人与性动交α欧美软件 | 免费看av在线观看网站| 成人黄色视频免费在线看| 黄网站色视频无遮挡免费观看| 男女免费视频国产| 亚洲 欧美一区二区三区| 在线观看免费视频网站a站| 精品国产一区二区久久| 麻豆精品久久久久久蜜桃| 制服丝袜香蕉在线| 在线观看免费高清a一片| kizo精华| 日本猛色少妇xxxxx猛交久久| videos熟女内射| 亚洲天堂av无毛| a级毛片黄视频| 精品国产一区二区三区久久久樱花| 午夜免费鲁丝| 热99久久久久精品小说推荐| 国产一区亚洲一区在线观看| av线在线观看网站| 欧美日韩视频精品一区| 曰老女人黄片| 国产精品久久久久久久电影| 国产1区2区3区精品| 午夜福利,免费看| 国产精品欧美亚洲77777| videos熟女内射| 看非洲黑人一级黄片| a级毛色黄片| 欧美精品一区二区大全| 成人无遮挡网站| 黄色一级大片看看| 制服人妻中文乱码| 精品一品国产午夜福利视频| 一本—道久久a久久精品蜜桃钙片| 成年av动漫网址| 国产 一区精品| 性色av一级| 亚洲精品日韩在线中文字幕| 丝袜脚勾引网站| 亚洲国产精品一区二区三区在线| 王馨瑶露胸无遮挡在线观看| 在线天堂中文资源库| 欧美性感艳星| 18+在线观看网站| 一级毛片电影观看| av黄色大香蕉| 日本wwww免费看| 麻豆乱淫一区二区| 亚洲精品aⅴ在线观看| 午夜91福利影院| 国产免费现黄频在线看| xxxhd国产人妻xxx| 宅男免费午夜| 男女国产视频网站| 日韩一区二区视频免费看| 一级片'在线观看视频| 久久精品国产鲁丝片午夜精品| 香蕉国产在线看| 麻豆乱淫一区二区| 日韩一本色道免费dvd| 精品一区二区三区视频在线| 九色成人免费人妻av| 欧美成人午夜免费资源| 美女主播在线视频| 啦啦啦啦在线视频资源| 午夜日本视频在线| 熟女人妻精品中文字幕| 国产成人精品无人区| 大香蕉97超碰在线| 在线天堂最新版资源| 99九九在线精品视频| 国产免费现黄频在线看| 高清不卡的av网站| 捣出白浆h1v1| 综合色丁香网| 在线精品无人区一区二区三| 久久午夜综合久久蜜桃| 另类亚洲欧美激情| 激情五月婷婷亚洲| 久久久精品免费免费高清| 亚洲内射少妇av| 亚洲国产看品久久| 欧美精品国产亚洲| 精品视频人人做人人爽| 欧美国产精品一级二级三级| 免费少妇av软件| 精品久久蜜臀av无| 一级爰片在线观看| 国产男人的电影天堂91| 欧美97在线视频| 久久久久久伊人网av| 建设人人有责人人尽责人人享有的| videosex国产| xxxhd国产人妻xxx| 考比视频在线观看| 婷婷色综合大香蕉| 99热这里只有是精品在线观看| 男女啪啪激烈高潮av片| 久久久久精品性色| 免费观看在线日韩| 欧美人与性动交α欧美软件 | 国产精品一区二区在线不卡| 免费看不卡的av| 国国产精品蜜臀av免费| 午夜福利乱码中文字幕| 日本猛色少妇xxxxx猛交久久| 国产又爽黄色视频| 爱豆传媒免费全集在线观看| 涩涩av久久男人的天堂| 亚洲伊人久久精品综合| 久久久久久人妻| 久久精品国产自在天天线| 欧美 日韩 精品 国产| 中文字幕人妻熟女乱码| 国产欧美日韩一区二区三区在线| 只有这里有精品99| 人妻系列 视频| 欧美日韩成人在线一区二区| 最近的中文字幕免费完整| 伊人亚洲综合成人网| 黄色视频在线播放观看不卡| 天天操日日干夜夜撸| 精品久久久精品久久久| 国产精品久久久久久久电影| 最近手机中文字幕大全| 狠狠婷婷综合久久久久久88av| av不卡在线播放| 纵有疾风起免费观看全集完整版| 曰老女人黄片| 22中文网久久字幕| 亚洲欧美日韩另类电影网站| 超色免费av| 亚洲国产欧美日韩在线播放| 日本午夜av视频| 18禁动态无遮挡网站| 国产国语露脸激情在线看| 三上悠亚av全集在线观看| 日韩精品有码人妻一区| 三上悠亚av全集在线观看| 日韩不卡一区二区三区视频在线| 久久久久久久国产电影| 国产精品一国产av| 飞空精品影院首页| 少妇人妻 视频| 日日啪夜夜爽| 大码成人一级视频| 一区二区日韩欧美中文字幕 | 午夜91福利影院| 欧美xxⅹ黑人| 国产老妇伦熟女老妇高清| 最近最新中文字幕大全免费视频 | 亚洲av综合色区一区| 黄片无遮挡物在线观看| 丝袜美足系列| 99国产综合亚洲精品| 国产亚洲精品久久久com| 中文天堂在线官网| 麻豆乱淫一区二区| 亚洲精品,欧美精品| 久久久精品区二区三区| 婷婷色综合大香蕉| 韩国精品一区二区三区 | 内地一区二区视频在线| 亚洲一级一片aⅴ在线观看| 一级爰片在线观看| 日韩大片免费观看网站| 一级爰片在线观看| 97在线视频观看| 亚洲性久久影院| 黄色怎么调成土黄色| videosex国产| 男人爽女人下面视频在线观看| 久久99蜜桃精品久久| 晚上一个人看的免费电影| 国产成人91sexporn| 新久久久久国产一级毛片| 亚洲国产欧美在线一区| 另类亚洲欧美激情| 亚洲 欧美一区二区三区| 大陆偷拍与自拍| 人妻少妇偷人精品九色| 哪个播放器可以免费观看大片| 久久久久久人妻| 高清av免费在线| 欧美激情国产日韩精品一区| 精品久久久精品久久久| 天天躁夜夜躁狠狠久久av| 欧美成人精品欧美一级黄| 99久久中文字幕三级久久日本| 考比视频在线观看| 日日爽夜夜爽网站| 精品熟女少妇av免费看| 久久久久国产精品人妻一区二区| 欧美人与性动交α欧美精品济南到 | 国产有黄有色有爽视频| 老司机亚洲免费影院| 22中文网久久字幕| 美女视频免费永久观看网站| 女人精品久久久久毛片| av视频免费观看在线观看| 久久精品久久精品一区二区三区| 精品国产一区二区三区久久久樱花| 国产精品久久久久久精品电影小说|