Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. We do know, however, that they existed over 5,500 years ago in ancient Asia.

    The oldest known transport wheel was discovered in 2002 in Slovenia. It is over 5,100 years old. Evidence suggests that wheels for transport didn't become popular for a while, though. This could be because animals did a perfectly good job of carrying farming tools and humans around.

    But it could also be because of a difficult situation. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren't going to be constructed until there was plenty of demand for them. Eventually, road surfaces did become smoother, but this difficult situation appeared again a few centuries later. There had been no important changes in wheel and vehicle design before the arrival of modem road design.

    In the mid-1700s, a Frenchman came up with a new design of road—a base layer (层) of large stones covered with a thin layer of smaller stones. A Scotsman improved on this design in the 1820s and a strong, lasting road surface became a reality. At around the same lime, metal hubs (the central part of a wheel) came into being, followed by the pneumatic tyre(充气轮胎) in 1846. Alloy wheels were invented in 1967, sixty years after the appearance of tarmacked roads (柏油路). As wheel design took off, vehicles got faster and faster.

    On the arrival of the graduation season, a large number of students will leave their colleges and get busy finding jobs. However, it seems not all students will be in a hurry to get to work. According to a survey online in May, about 9.8 percent of the 93,420 graduates surveyed said they wouldn't begin working right after graduation. This phenomenon is called "delayed employment".

    One reason why the graduates don't start their careers immediately is that they want a job related to their personal interests, and they are unwilling to give in and take jobs they don't like. "Looking for the right career is like looking for Mr. Right. Maybe I could have found a job or two, but I don't want to just make a living or be stuck in a specific position,” said Shen Yu, who graduated in 2014 but didn't look for a job right away.

    Another reason is to avoid the fierce competition of the job market.Statistics provided by the Ministry of Education show the number of the new university graduates will reach 7.95 million this year. Meanwhile, only 26.7 percent of the new graduates have signed contracts(合同) with employers, 8.7 percent down from the previous year.

    And some Chinese college students have chosen to travel or volunteer instead of finding jobs. For example, Chen Nuan, who will graduate from the Shanghai Institute of Visual Arts this summer, has planned to tour Europe immediately after graduation. "As the old Chinese saying goes,traveling thousands of miles is better than reading thousands of books,"she told China Daily.

    However, no matter what you choose after graduation, make full use of the first few years—this is when people develop soft skills such as punctuality and teamwork. The first 10 years are essential, which shapes careers in the long term.

    Learning any language is hard, but learning English can be especially challenging. Why? Because native speakers use the language in ways that textbooks could never describe. In particular, words that British people use cause many language students to scratch their heads.

    Here's an example: You overhear a Briton calling someone a “wazzock”. But what exactly is a wazzock? This word, in fact, means a foolish person, although there's nothing about it that would help you guess that. There are many strange terms like this in British English – the Oxford English Dictionary would be much smaller without these peculiar (古怪的) usages filling its pages.

    How can these odd words be explained? Part of the answer is the British sense of humor. Britons don't like to take things too seriously, and this is evident through many British words and phrases. For example, to “spend a penny” means to use the bathroom. It refers to the days when people had to pay a penny to use a public toilet.

    In an interview for the BBC's website, British linguist David Crystal suggested there may be historical reasons for the sheer number of odd words and phrases in British English. He thinks that they began in the late 16^th and early 17^th centuries. This was a great age for the theater, when Shakespeare and other writers worked hard to keep up with the demand for new plays. The theater's popularity also created an incentive (刺激) to invent new words.

    With this in mind, perhaps Shakespeare and his peers are to blame for unusual British words such as “codswallop” and “balderdash” – which both, ironically, mean “nonsense”.

    While these strange words may be confusing to non-native speakers, they certainly make studying English a lot more interesting.

    Every city, in fact, can be felt by its warmth-not in terms of its natural climate but its human touch.

    About twenty years ago, I arrived in Australia. Searching for a place in a map in the street, I was approached by an elderly man who asked “How are you? Are you lost? How can I help you?”, which really impressed and warmed me. Another time, as I was pushing my bike on the sidewalk one night, a young lady shouted to me: “Carry me please” and then jumped onto my bicycle. While we had a little chat, she got where she wanted and hopped off my bike with “Thanks, bye!” At that moment, I had a sense as much of pleasant surprise as of “being trusted”.

    Still in Australia, two of my friends decided to hitch（搭便车）their way to Sydney in order to save money. A young driver stopped, and luckily he was also going to Sydney, so he let them in and even allowed them to drive while he went to sleep on the back seat. About eight hours later, they arrived and he woke up. Saying thanks to each other, they went their separate ways.

    In my opinion, no matter how developed and advanced it is, if in general a place presents itself with a cold and indifferent（冷漠的）face to people, especially to strangers, even keeping them highly alert（警惕的）not to be cheated all the time, can perhaps hardly be classified as a land of civilization（文明）. In a sense, the attitude towards strangers that the people have in the city mirrors its warmth.

    Parents and kids today dress alike, listen to the same music, and are friends. Is this a good thing? Sometimes, when Mr. Ballmer and his 16-year-old daughter, Elizabeth, listen to rock music together and talk about interests both enjoy, such as pop culture, he remembers his more distant relationship with his parents when he was a teenager.

    “I would never have said to my mom, 'Hey, the new Weezer album is really great. How do you like it?''' says Ballmer. “There was just a complete gap in taste.”

    Music was not the only gulf. From clothing and hairstyles to activities and expectations, earlier generations of parents and children often appeared to move in separate orbits.

    Today, the generation gap has not disappeared, but it is getting narrow in many families. Conversations on subjects such as sex and drugs would not have taken place a generation ago. Now they are comfortable and common. And parent-child activities, from shopping to sports, involve a feeling of trust and friendship that can continue into adulthood.

    No wonder greeting cards today carry the message, “To my mother, my best friend.”

    But family experts warn that the new equality can also result in less respect for parents. “There's still a lot of strictness and authority on the part of parents out there, but there is a change happening,” says Kerrie, a psychology professor at Lebanon Valley College. “In the middle of that change, there is a lot of confusion among parents.”

    Family researchers offer a variety of reasons for these evolving roles and attitudes. They see the 1960s as a turning point. Great cultural changes led to more open communication and a more democratic process that encourages everyone to have a say.

    “My parents were on the 'before' side of that change, but today's parents, the 40-year-olds, were on the 'after' side,” explains Mr. Ballmer, “It's not something easily accomplished by parents these days, because life is more difficult to understand or deal with, but sharing interests does make it more fun to be a parent now.”

"Having the world at our fingertips" is a metaphor often used when we put our hands on information technology, like smartphones and computers. This is a good metaphor. But what is much better is how we use our hands to make things done.

Put one hand flat on a surface, palm down, and you might be able to make out the outline of 14 short bones in your thumb and fingers, in addition to 5 longer ones in your palm that are jointed to your wrist. These bones give each hand its rigid, knuckled structure. Together they're critical components of the anatomical （解剖的） architecture that allows your hand to move. At each of your fingertips there's an ever-growing, translucent plate of fibrous protein, otherwise known as a nail. Although they're nice for decoration, your nails protect and enhance your sensitivity to touch, too.

Imagine squeezing a piece of paper between your thumb and index finger, for example. We use this type of forceful pad-to-pad precision grasping without thinking about it, and literally in no time. Yet it was a breakthrough in human evolution. Other primates （灵长目动物） exhibit some kinds of precision grasps in the handling and use of objects, but not with the kind of efficiency that our hand does.

With a unique combination of traits, the human hand shaped history. No question, stone tools couldn't have become a keystone of human technology without hands that could do the job, along with a nervous （神经的） system that could regulate and coordinate the necessary signals. Even for those who have never attempted to make a spear tip or arrowhead from a rock, it's obvious that it would require strong grasps, constant rotation and repositioning, careful strikes with another hard object. And even for those who have done so, it can be a bloody business.

Of course, the most common object that people touch nowadays is a screen. And the tap-tap-tap movement of our fingers is a unique human ability, as no other primate can move their fingers as rapidly and independently as we do. Here again, we can thank the extraordinary human brain given that normal finger tapping requires the functional integrity of different parts of our central nervous system.