Robyn Lee， a 15-year-old teenage girl who studies at York Community High School， US says she has four friends. But she also has 15 to 20 other friends she considers part of her regular social circle.

“It's like a bad thing to have only one， friend ，”explained Robyn. “If you have one friend， it means only one person likes you. That’s not cool，” she said.

For many years， experts studying teen friendships have known that teenagers prefer to travel in groups. In studies conducted in 1963 and in 1995， researchers found teen friendship groups averaged six people. In 2005， when teens were asked about how many friends they kept in touch with regularly， the average answer was 20.

The change to bigger -group friendships has advantages， such as increasing more connections and improving teens' self-pride by giving them a place to belong.

However， the change also has some disadvantages，say psychologists. “The meaning of friendship is becoming much more complicated，” said Bernardo Carducci， a professor of psychology at Indiana University Southeast.

MaryRose Moss， a 17-year-old in Chicago， knows how she could get more friends. She created a Facebook page when she was 14 and within months ， she had her group of 500 friends.

Text messaging has opened the door to many new connections， she says. “I'm friends with some people that I wouldn't be as close to if it weren't for technology，” said Moss. “It's so easy to send a text to somebody even if you don't know him very well. ”

Some psychologists wonder whether social-networking technology is affecting some skills children once got from making friends in the old-fashioned way.

“In the past， you argued， discussed and reached an agreement， but if somebody disagrees with you now， you can ‘defriend’ him with the click of keys，” said Carducci.

Marianne Boe， a social studies teacher in Chicago ， sees signs of changing friendships in the hallways. Ten years ago， she could easily know groups of girls who stayed friends through all four years of high school. “Today， it's harder，” Boe said.

   Cellphones, tablets, and computers are keeping children and teenagers awake at night-even when they' re not in use, according to new research. A study published on Monday in JAMA Pediatrics says that media devices are causing kids to sleep less and reducing the quality of sleep that they get. This leads to trouble of staying awake the next day.

Researchers analyzed hundreds of studies of children and teens aged 6-19. The scientists found a strong and consistent association between the use of technology at bedtime and poor sleeping. The reason is not just that kids are staying up too late with their devices. Using a computer can overstimulate the mind and emotions, the researchers say. A smartphone or tablet also gives off a light that affects the body's natural timing. These factors contribute to poor quality sleep. And many kids could be at risk. According to the study,72% of all children and 89% of adolescents have at least one device in their sleep environment. Most of these devices are used near bedtime.

"The harmful association between screen-based devices and kids' sleep is a major public health concern," the study concludes. In their conclusion, the researchers urge parents to understand the damaging influence of device use before sleep.

   Everybody sleeps，but what people stay up late to catch or wake up early in order not to miss varies by culture.

From data collected，it seems the things that cause us to lose the most sleep，on average，are sporting events，time changes，and holidays.

Around the world，people change sleep patterns thanks to the start or end of daylight-saving time（夏令时间）. Russians，for example，began to wake up about a half-hour later each day after President Vladimir Putin shifted the country permanently to“winter time”starting on October 26.

Russia's other late nights and early mornings generally correspond（相一致）to public holidays. On New Year's Eve，Russians have the world's latest bedtime，hitting the hay at around 3:30 a. m.

Russians also get up an hour later on International Women's Day，the day for treating and celebrating female relatives.

Similarly，Americans' late nights，late mornings，and longest sleep fall on three-day weekends.

Canada got the least sleep of the year the night it beat Sweden in the Olympic hockey（冰球）final.

The World Cup is also chiefly responsible for sleep deprivation. The worst night for sleep in the U. K. was the night of the England-Italy match on June 14. Brits stayed up a half-hour later to watch it，and then they woke up earlier than usual the next morning thanks to summer nights，the phenomenon in which the sun barely sets in northern countries in the summertime. That was nothing，though，compared to Germans，Italians，and the French，who stayed up around an hour and a half later on various days throughout the summer to watch the World Cup.

It should be made clear that not everyone has a tool to record their sleep patterns；in some of these nations，it's likely that only the richest people do. And people who elect to track their sleep may try to get more sleep than the average person. Even if that's the case，the above findings are still striking. If the most health-conscious among us have such deep swings（明显改变）in our sleep levels throughout the year，how much sleep are the rest of us losing？

   Nowadays, I acknowledge that a revolution has occurred. That much has been ___ by having hand-held iPads or smart phones that allow us not only to communicate while on the _____ but also to reserve parking spaces, get weather reports, and _____ tell us where, at any given moment, we are standing on the planet Earth.

But I must acknowledge a _____. Conversation used to be surprisingly _____ to start. When I took a seat next to someone on a train, bus, or plane, the first thing I would do was _____ the person. Once the ice had been broken, the following chat _____ erupt naturally.

Time has changed, and the change has been _____. Recently, while I was _____ a long distance bus, I couldn't help but notice everyone was staring at their ______, clicking. I found an empty seat next to a middle-aged man and said "Morning" to him. He threw me a ______ and said "Morning". Then he returned to his ______. So I left him in his world.

I miss the ______ conversations with fellow travelers. One never knows what will be ______, and in fact, sometimes how ______ it will be. I was once on a ______ traveling from Iceland to Denmark. I noticed an old man looking out over the North Sea. "It's beautiful, isn't it?" I said. He turned to me,______, and we were soon chatting away. _____ I told him that I didn't know how I was going to get from the port in Denmark to my destination city. He ______,"Of course you know. I have a car and I'm going to ______ you there. "

   Around the world more and more people are taking part in dangerous sports and activities. Of course there have ___________ been people who have looked for adventures —those who have climbed the _______ mountains，explored unknown parts of the world or _______ in small boats across the greatest oceans. Now，however，there are people who look for the immediate _______ from a dangerous activity which may only last a few minutes or even _________.

I would consider bungee jumping to be a good example of such an activity. You jump from a high place about 200 meters above the ground with an elastic（有弹性的）rope ___________ to your ankles. You _________ at up to 150 kilometers an hour until the rope stops you from _________ the ground. It is said that 2 million people around the world have now _______ bungee jumping. Other activities，which most people would say are as __________ as bungee jumping，____________ jumping from tall buildings and ____________ into the sea from the top of high rocks.

Why do people take part in such activities？Some psychologists（心理学家）say that it is __________ life in modern society has become safe but __________ .In the past，people's lives were constantly under __________. They had to go out and hunt for __________，and life was a continuous battle for survival.

Nowadays, ______________ many people, life offers little excitement. They live and work in relatively safe conditions; they ____________ food in shops; and there are doctors and hospitals to take ____________ of them if they become ill. The answer for some of these people is to ____________ danger in activities such as bungee jumping.