As the population of the planet increases, so does the number of homes, business, parking lots, schools, airports and roadways. All these structures use electricity and need to be lighted. Humans demand light. They want their homes more comfortable and they want their streets safe. The problem is that researchers are finding that all the light is having a negative effect on humans and wildlife as well.

    Less than 10 years ago I drove to a thinly populated section of my own, lay down in the middle of the road and watched an attractive meteor shower(流星雨). If I did that today, I wouldn't be able to see the meteor shower.

    Nowadays scientists are finding light pollution can be almost as bad as carbon dioxide （二氧化碳）pollution. One of the saddest parts of light pollution is that most of it is unnecessary and most of the outdoor light that we use is wasted. One only needs to look at a row of street lights to see how much of the lights shines upwards and lights the sky: a total waste of electricity.

    Additionally, the production of electricity creates pollution by releasing greenhouse gases. This affects the air we breathe and our quality of life.

    Scientists are also studying the effects of light pollution on wildlife. Thousands of birds die each year when they crash into highly lighted buildings, as they become puzzled by the light. It has been long known that tiny baby sea turtles become lost and follow the light on the shore instead of heading towards the sea.

    Fortunately, light pollution is one of the easiest sources of pollution that can be corrected without a negative effect. Following some guidelines and a little searching on Google can give you many ideas on how to reduce your contribution to light pollution.

    Suppose you become a leader in an organization. It's very likely that you'll want to have volunteers to help with the organization's activities. To do so, it should help to understand why people undertake volunteer work and what keeps their interest in the work.

    S Let's begin with the question of why people volunteer. Researchers have identified several factors that motivate people to get involved. For example, people volunteer to express personal values related to unselfishness, to expand their range of experiences, and to strengthen social relationships. If volunteer positions do not meet these needs, people may not wish to participate. To select volunteers, you may need to understand the motivations of the people you wish to attract.

    S People also volunteer because they are required to do so. To increase levels of community service, some schools have launched compulsory volunteer programs. Unfortunately, these programs can shift people's wish of participation from an internal factor (e.g. “I volunteer because it's important to me”) to an external factor (e.g. “I volunteer because I'm required to do so”). When that happens, people become less likely to volunteer in the future. People must be sensitive to this possibility when they make volunteer activities a must.

    S Once people begin to volunteer, what leads them to remain in their positions over time? To answer this question, researchers have conducted follow-up studies in which they track volunteers over time. For instance, one study followed 238 volunteers in Florida over a year. One of the most important factors that influenced their satisfaction as volunteers was the amount of suffering they experienced in their volunteer positions. Although this result may not surprise you, it leads to important practical advice. The researchers note that attention should be given to “training methods that would prepare volunteers for troublesome situations or provide them with strategies for coping with the problem they do experience”.

    S Another study of 302 volunteers at hospitals in Chicago focused on individual differences in the degree to which people view “volunteer” as an important social role. It was assumed that those people for whom the role of volunteer was most part of their personal identity would also be most likely to continue volunteer work. Participants indicated the degree to which the social role mattered by responding to statements such as “Volunteering in Hospital is an important part of who I am.” Consistent with the researchers' expectations, they found a positive correlation(正相关) between the strength of role identity and the length of time people continued to volunteer. These results, once again, lead to concrete advice: “Once an individual begins volunteering, continued efforts might focus on developing a volunteer role identity....Items like T-shirts that allow volunteers to be recognized publicly for their contributions can help strengthen role identity”.

    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(JT) their heads.

    Here's an example: You happen to hear 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 strange 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 16th and. early 17th centuries. This was a great age for the theatre, when Shakespeare and other writers worked hard to keep up with the demand for new plays. The theatre'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.

    TV, iPads, and computers are fun and sometimes educational, but many people think the technology is bad. My parents let me watch one or two shows or play a game on the iPad for an hour, but then make me find thing else to do, like read or draw a picture. They say that too much screen time won't help me become smarter.

    I think that it is okay to watch TV, but not too much. And some of my friends agree.

    "A tiny bit of screen time is okay," Mateo J., 7, said. "But too much of it is not good for your brain."

    Though my friends and I sometimes complain (抱怨), we think that it's good our parents limit our screen time.

    "Our parents should limit our technology time because otherwise you might get carried away and not even know that you've stayed inside all day watching TV," Naomi J. , 9, said.

    The American Academy of Pediatrics(AAP) used to recommend (推荐) that parents let kids have about two hours of screen time per day, but in 2016, they started recommending that parents of kids 6 and older decide for themselves how much time is okay, as long as the shows and games are appropriate. The AAP still says that kids 2-5 years old should have only about one hour of screen time per day, and kids under 2 no screen time at all. The AAP says that media you've stayed inside all day in all forms, including TV, computers, and smartphones, can affect how children feel, learn, think, and behave. However, parents are still the most important influence.

    I think TV shows like Brain Games and Cupcake Wars are inspiring. I've even learned some magic while watching Brain Games! Video games can be educational, as some TV shows are about nature, and other shows have useful messages. But some games and shows have bad things in them, like smoking.

    You can play outside instead of watching TV. Find other things to do. You don t have to be or screens all day.

    People like to post their selfies(自拍照) on social media. To know more about it, scientists at Syracuse University in New York recently did a research and came up with some surprising findings.

    People who post selfies and use editing software to make themselves look better show behavior connected to narcissism(自恋), the researchers said. Makana Chock, a professor from Syracuse University, said because social media is mostly used by people to share unimportant information about their lives, it is a good place for people to "work towards satisfying their own vanity." Those "likes" under their Facebook selfies make them feel good.

    Besides, people who post group selfies show a need for popularity and a need to belong to a group, the research found. Some people feel "peer(同伴) pressure" to post selfies and some follow the popular belief that if there is no picture of an event or experience, it did not really happen. "Anyway, it shouldn't be seen as negative. People get sense of satisfaction especially when they get likes. And it does no harm," Chock said.

    Other findings from the study include: There are no major differences on how often men and women post selfies and how often they use editing software. But men who post selfies showed more of a need to be seen as popular than women who posted selfies.

Chock said posting selfies on social media is not all that different from what people have done for many years. On trips and special events, our parents and grandparents used cameras instead of phones to take photos. They would bring back photos to show friends and family. You had no choice but to look at them. You probably commented about how nice everyone in the photos looked, especially children and the person showing the photos. They were happy to hear your comments. That was the old way of "clicking like". On social media, however, people can decide not to look at photos — even if they click "like".

In life, once on a path, we tend to follow it, for better or worse. What's sad is that even if it's the latter, we often accept it anyway because we are so used to the way things are that we don't even recognize that they could be different. This is a phenomenon psychologist call functional fixedness.

This classic experiment will give you an idea of how it works and a sense of whether you may have fallen into the same trap: People are given a box of tacks (大头钉) and some matches and asked to find a way to attach a candle to a wall so that it burns properly.

Typically, the subjects try tacking the candle to the wall or lighting it to fix it with melted wax. The psychologists had, of course, arranged it so that neither of these obvious approaches would work. The tacks are too short, and the paraffin (石蜡) doesn't stick to the wall. So how can you complete the task? The successful technique is to use the tack box as a candle-holder. You empty it, tack it to the wall. and stand the candle inside it. To think of that, you have to look beyond the box's usual role as a receptacle just for tacks and re-imagine it serving an entirely new purpose. That is difficult because we all suffer to one degree or another from functional fixedness.

The inability to think in new ways affects people in every corner of society. The political theorist Hannah Arendt coined the phrase" frozen thoughts" to describe deeply held ideas that we no longer question but should. In Arendt's eyes, the self- content reliance on such accepted "truths" also made people blind to ideas that didn't fit their worldview, even when there was plenty of evidence for them.

Frozen thinking has nothing to do with intelligence. She said," It can be found in highly intelligent people."