For many people, selfies(自拍照) have been so popular as to be a must. New hairstyle? Snap a selfie. Dining out? Selfie. They’ve even been taken from beyond Earth’s atmosphere. A Japanese astronaut, Aki Hoshide, snapped one while visiting the International Space Station. In what may be one of the coolest selfies of all time, Hoshide caught his likeness alongside the sun, Earth, a robotic arm. a spacesuit and the inky darkness of the universe. In 2013, Oxford Dictionaries even crowned “selfie” as the word of the year.

It isn’t difficult to judge someone’s mood when a selfie is snapped—the images are, by their very nature, mood-driven. Whether you capture yourself with a smile or a fierce facial expression, scientists are figuring out ways to study self-portraits taken by smart phones and analyze what they say about you. Selfie studies will allow them to predict not only the subject’s mood, but also the mood of an entire region. A team of researchers led by Dr. Lev Manovich of the City University of New York has been studying thousands of Instagram self-portraits in select cities, including Bangkok, Berlin, Moscow, New York and Sao Paulo, to analyze how mood affects selfie poses. While many wondered if it was even possible to determine an entire city’s mood based on a smattering of self-portraits, the study has delivered promising results. Among the most interesting findings: People in Moscow smile the least of all the selfie cities that were analyzed, while Bangkok and Sao Paulo selfie subjects looked the happiest. The researchers were even able to uncover data on gender and age differences: On the whole, women were more expressive than men in their self-portraits, but men older than 30 were more likely to post selfies on Instagram than women.

Another study, started by Manovich and researchers from the University of California, San Diego and the City University of New York, studied 1 million selfies posted on Twitter. Is it possible to judge a person’s mood, or even a city’s mood from a selfie? The answer, researchers say, is yes. They posit(断定) the ability to measure “happiness” of geographic regions using selfies and hope to use the method as an alternative to traditional surveys.

(1) Hello. It’s one of the first words we learn as babies, yet it’s one of the last ones we think to use as adults. That’s unfortunate, because saying hello is more than just saying hello—it is recognition of another’s worth. How might the world change—how might we change—if we mastered this word? To find out, I spent one month saying hello to every person I met. Here’s what I’ve learned.

(2) It can boost (促进) productivity. In one of the few studies ever done on this subject, Allan

Allday, an assistant professor of special education at Oklahoma State University, had middle school teachers greet their students individually each morning. This exchange of greetings raised the kids’ productivity. School went from impersonal to personal, and that resulted in more class participation and better grades.

(3) Environments influence friendliness, One study found that people in the city were kiss likely to one hands with a stranger than those in the countryside. And researchers say, pleasure environments generally encourage more smiles and hellos than unpleasant ones. My experience was similarly. Whatever the reason, my urban hellos were answered far less often than my rural one. Similarly, people in vacation spots, like the Jersey Shore, were far friendlier than those hurrying work downtown.

(4) It’s a form of universal health insurance. It’s impossible to say hello without smiling. And smiling has been shown to lower blood pressure, relieve stress and boost happiness. Apparently, a smile creates a similar effect in the recipient (接受者)。

(5)So maybe we can make the world a better place by____________. After a month of doing it. I feel lighter and more connected and I have a better sense of well-being.

Obesity(肥胖) has become a serious problem now. According to a recent survey, teenage obesity has increased at an alarming rate across America. Teenage obesity is mainly due to the increased consumption (消耗) of junk food which contains large amounts of fat. This has exposed the teens to a 14% greater risk of having a heart attack as well as seriously high blood pressure.

Various causes of teen obesity have been claimed, the most important of which is having insufficient physical exercise on the teens’ part. It is argued that teens nowadays who lack sufficient physical exercise and have unhealthy eating habits are more likely to be obese. Nowadays, a main part of the teenagers spend their spare time on the computer, television or perhaps simply playing games. This greatly limits any kind of physical activity of the teenager. According to a recent survey, around 43% of teenagers spend more than 2 hours watching television every single day.

Long time inactivity in addition to the ill eating habits has increased the chance of obesity in teenagers even more. However, this does not mean that teens do not do enough exercise, but the amount which they do, is certainly not enough as compared to their intake of fatty foods. Besides this, parents need to change the whole lifestyle of the family in order to develop a healthier lifestyle of their children.

The teenagers must also be encouraged to take part in other physical activities which require more effort; such as playing basketball, tennis, badminton, volleyball and swimming. Meanwhile, the teenagers also need to be educated on the ill effects of junk food and must be asked to avoid them as much as possible. Their diet must also be made healthier and more balanced, which will help them in losing more weight quickly. For better guidance on reducing the teens’ weight quickly, parents can always turn to a doctor.