How to deal with waste has been a problem since humans started producing it. As more and more people choose to live close together in cities, the waste-disposal (处理) problem becomes increasingly difficult.

    During the eighteenth century, it was usual for several neighboring towns to get together to select a faraway spot as a dump site. Residents or trash haulers (垃圾拖运者) would transport household rubbish, rotted wood, and old possessions to the site. Periodically (定期的) some of the trash was burned and the rest was buried. The unpleasant sights and smells caused no problem because nobody lived close by.

    Factories, mills, and other industrial sites also had waste to be disposed of (处理). Those located on rivers often just dumped (倾倒) the unwanted remains into the water. Others built huge burners with chimneys (烟囱) to deal with the problem.

    Several facts make these choices unacceptable to modem society. The first problem is space. Dumps, which are now called landfills, are most needed in heavily populated areas. Such areas rarely have empty land suitable for this purpose. Property is either too expensive or too close to residential (住宅区的) neighborhoods. Long-distance trash hauling has been a common practice, but once farm areas are refusing to accept rubbish from elsewhere, cheap land within trucking distance of major city areas is almost nonexistent (不存在).

    Awareness (意识) of pollution dangers has led to more strict rules of waste disposal. Pollution of rivers, ground water, land and air is a price people can no longer pay to get rid of waste. The amount of waste, however, continues to grow.

    Recycling efforts have become commonplace, and many towns require their people to take part. Even the most efficient recycling programs, however, can hope to deal with only about 50 per cent of a city's reusable waste.

    Everything has a name. All people, places and things have names. For example, Jenny is the name of a student from England. England is the name of her country. Cities and towns have names, too. Schools and office building also have names. All things have names. Names are important.

    Names are different all over the world. In Jenny's class, Jenny must learn the names of students from all over the world. This is very difficult because the names are different.

    In the USA, most people have a first name, a middle name, and a last name. Parents choose the first and middle names for their baby. There are names for boys and names for girls. For example, John, Peter, Tom and Mike are all names for boys. Elizabeth, Betty, Susan, and Mary are all names for girls. The last name is the family name. Usually it is the father's family name. In a family, the mother, the father, and the children usually have the same last name.

    Names are different all over the world. They can be long or short, but they are always very important.

    "Cleverness is a gift while kindness is a choice. Gifts are easy – they're given after all. Choices can be hard." –– Jeff Bezos.

    I got the idea to start Amazon 16 years ago. I came across the fact that the Internet usage was growing at 2,300 percent per year. I'd never seen or heard of anything that grew that fast, and the idea of building an online bookstore with millions of titles was very exciting to me. I had just turned 30 years old, and I'd been married for a year. I told my wife MacKenzie that I wanted to quit my job and go to do this crazy thing that probably wouldn't work since most start-ups don't, and I wasn't sure what to expect. MacKenzie told me I should go for it. As a young boy, I'd been a garage inventor. I'd always wanted to be an inventor, and she wanted me to follow my passion.

    I was working at a financial firm in New York City with a bunch of very smart people, and I had a brilliant boss that I much admired. I went to my boss and told him I wanted to start a company selling books on the Internet. He took me on a long walk in Central Park, listened carefully to me, and finally said, "That sounds like a really good idea, but it would be an even better idea for someone who didn't already have a good job." That logic made some sense to me, and he persuaded me to think about it for 48 hours before making a final decision. Seen in that light, it really was a difficult choice, but finally, I decided I had to give it a shot. I didn't think I'd regret trying and failing. And I believed I would always be haunted(萦绕)by a decision to not try at all.

    After much consideration, I took the less safe path to follow my passion, and I'm proud of that choice. For all of us, in the end, we are our choices.

    Your DNS cache (域名存储器) stores the locations (IP addresses) of web servers that contain web pages which you have recently viewed. If the location of the web server changes before the entry in your DNS cache updates, you can no longer access the site.

    If you encounter a large number of HTML 404 error codes, you may need to clear your DNS cache. After you clear your DNS cache, your computer will query(询问) nameservers (域名服务器) for the new DNS information. The following methods allow you to remove old and inaccurate DNSinformation that may result in 404 errors.

    Windows 7

    To clear your DNS cache if you use Windows 7, perform the following steps:

    Click Start.

    Enter cmd in the Start menu search text box.

    Right-click Command Prompt and select Run as Administrator.

    Run the following command:

    Ipconfig/flushdns

    If the command succeeds, the system returns the following message: Windows IP configuration successfully flushed the DNS Resolver Cache.

    Windows® 8

    To clear your DNS cache if you use Windows 8, perform the following steps:

    On your keyboard press Win+X to open the WinX Menu.

    Right-click Command Prompt and select Run as Administrator.

    Run the following command:

    Ipconfig/flushdns

    If the command succeeds, the system returns the following message: Windows IP configuration successfully flushed the DNS Resolver Cache.

    Windows XP, 2000, or Vista®

    To clear your DNS cache if you use Windows XP, 2000, or Vista®, perform the following steps:

    Click Start.

    On the Start menu, click Run.

    If you do not see the Run command in Vista, enter run in the Search bar.

    Run the following command: ipconfig/flushdns

    If the command succeeds, the system returns the following message: Successfully flushed the DNS Resolver Cache.

    MacOS® 10.10.4 and above

    To clear your DNS cache if you use MacOS X version 10.10.4 or above, perform the following steps:

    Click Applications.

    Click Utilities.

    Click Terminal.

    Run the following command:

    sudo killall-HUP mDNSResponde

    If the command succeeds, the system does not return any output(输出信息).

Warning:

    To run this command, you must know the computer's administrator account password.

    In Britain. Boxing Day is usually celebrated on December 26th, which is the following day after Christmas Day. However, strictly speaking, Boxing Day is the first weekday after Christmas. Like Christmas Day, Boxing Day is a public holiday. This means it's a non-working day in the whole of Britain. When Boxing Day falls on a Saturday or Sunday, the following Monday is the public holiday.

    The exact origin(起源)of the holiday is unclear. One of the thoughts is that during the Middle Ages, when great sailing ships were setting off to discover new land, a Christmas Box was placed by a priest(神父)on each ship. Those sailors who wanted to ensure a safe return would drop money into the box. It was sealed up and kept on board until the ship came home safely. Then the box was handed over to the priest in exchange for the saying of a mass of thanks for the success of the sailing. The priest wouldn't open it to share the contents with the poor until Christmas.

    One more thought is about the "Alms Box" placed in every church on Christmas Day. Worshippers(做礼拜的人) put gifts for the poor into it. These boxes were always opened the day after Christmas. That is why that day became known as Boxing Day.

    Today, many businesses, organizations and families try to keep the traditional spirit of Boxing Day alive by donating(捐赠) their time, services and money to aid Food Banks, providing gifts for the poor, or helping families in need. Besides, spending time with family and shopping are popular Boxing Day activities now.

Robots have long been drawing inspiration from animals, with the creation of robot dogs or snake-shaped robots. And yet, the field of robotics is far less enthusiastic about the other kind of living things—plants. Barbara Mazzolai, an Italian roboticist owes this to a misconception about plant behavior: that they cannot move or think. "It's not true at all, " she says. To challenge this view, Dr Mazzolai and her team recently launched a machine called "FiloBot", a robot based on a climbing species. 

To survive, a climbing plant must switch between several different behaviors. In forest environments, it must first grow out of the soil and travel along the ground in search of a support to hold onto, such as a nearby tree. Once a support is located, though, the plant fixes itself around the object and then growing towards the light. To choose the best angle to grow upwards, a climbing plant uses its shoots(芽) to receive information about light and gravity. 

FiloBot has sensors on its main shoot. It can 3D-print its body with plastic and grow at a controllable rate. These functions, researchers found, enabled FiloBot to cross gaps, and find things to attach to. The lack of heavy on-board computing device means that it is light and requires minimal care, while its slow pace means that it doesn't disturb things around it, making it possible to move through a complex, unseen environment, or monitoring disaster sites. 

For now, FiloBot is still being tested. Its tendrils(卷须) have not left the laboratory. Still, it has already been employed in deconstructing plant behaviour. For example, it was long assumed that climbing plants find their supports by growing towards shade, though the exact mechanism was unclear. FiloBot could imitate this behaviour by detecting far-red light, which is typical of shaded areas, providing clues to how plants do it. 

Dr Mazzolai hopes that such projects will inspire other roboticists to take their cues from plants and develop completely new technologies.