Bees and other pollinators（传粉者）  use smells to track down fresh flowers. Air pollutants can weaken those scents（气味）.  Scientists had worried this might make it harder for some pollinators to find a meal.

    Many animals help pollinate plants. Species that do this include bees, butterflies, etc. But for many reasons, the pollinators available to help plants in this way are decreasing. Scientists think a loss of habitat（栖息地）can be one factor. Diseases and exposure to poisonous chemicals also count.

    Jose Fuentes points to air pollution as another possible factor. He's an atmospheric scientist at Pennsylvania State University. In an earlier study, he showed some air pollutants could weaken or destroy scents emitted(发出)by flowers.

    Searching for a meal leaves pollinators out in the open and at risk of becoming other animal's lunch. And any time spent hunting food is time away from their duties back home, like protecting a hive（蜂巢）or nest, explains T'ai Roulston. He's an insect biologist at Virginia University. Roulston worked with Fuentes on the new study.

    In the study, the researchers focused on five kinds of representative scent molecules(分子)plants emit. One molecule they looked at, for example, is called beta-myrcene. Many flowers give off this chemical into the air.  Normally, this gas can travel some 800 meters from its flower source. But in polluted air, this same molecule could travel only half as far.

    Worse still, air pollution might do more than just weaken scent plumes（气味烟云）．Chemical reactions between air pollutants and plumes may transform the flowers' smells, creating new scents. And these scents may be unrecognizable to pollinators.

    That's certainly Fuentes' concern.  So, he says his next research project will look at how insects handle any new flower scent. "It's possible that some insects will change ways to detect and use these new molecules to find food," he says.

    More and more comment(评论) sections are being shut down online.

    Autumn Phillips had had enough. On August 19, the executive editor of the Quad-City Times in Iowa, and Illinois, US visited her website, qutimes. com, and saw a story about a man who had been shot to death. When she got to the readers' comments section at the end, she was shocked by what she saw. Below the story was a growing string of comments—a racist remark about democratic( 民主的) voters, a negative comment about police...So Phillips decided to do something she had been thinking about for a long time: she shut down the comment section.

    Phillips was not alone in making such a move. Last week, NPR announced it too was closing its online comments section. The decisions don't mean that the news outlets are no longer interested in what their audiences are thinking. Both stressed their eagerness to hear from readers and listeners on social networks. But both agreed that comments had deviated from their original intention. And so they had.

    In the early days of digital journalism, comments were seen as a key part of the new media, a wonderful opportunity for strengthening the dialogue between news producers and their audiences. It was a welcome change, given that for long many news organizations were far too separated from their readers. Much more back and forth conversation seemed like healthy and welcome evolutions. Sadly, that's not the way things turned out. Rather than a place for exchanging ideas, comments sections became the home of ugly name-calling, racism and anti-women language. Besides their poisonous quality, comments seem out of place today.

    “Since we made the announcement, I've received an outpouring of responses from our readers,”she says. “I've heard from parents whose children were hurt by our online comments. I've heard from people who said they wouldn't send in letters to the editor because they were attacked so fiercely by comments, and it wasn't worth it.”

    Dodder is an unusual and unwanted plant that attacks other plants. Except for its flowers, the plant looks like spaghetti, a kind of noodles in the shape of long thin pieces that look like string when they are cooked. It's almost leafless, thread-like stems hang down on top of other plants that dodder needs to stay alive. Dodder does not produce its own food. Instead, it steals food from other plants. It feeds by sucking juices from the plant which is wrapped around, often making its host very weak or even killing it.

    Dodder can find other plants by their smell. When a young dodder plant starts growing, it follows the smell of plants it prefers, like tomato plants, potato plants, or other farm crops. Unlike most plants that usually grow in the direction of light or warmth, a dodder plant will grow in the direction of, for example, tomato smell—if a tomato happens to be growing nearby.

    However, a young dodder plant must find a host plant quickly. It no longer needs its root once it is attached to the host and wrapped around it. If it cannot catch a smell of a potential host within a few days, it will dry up and vanish even if there is plenty of water around. Once it finds a host, the young dodder plant will attach itself to it and start growing faster. At that point the dodder plant will drop its root.

    Dodder is thus a difficult weed to manage and a real headache for farmers. When it does get out of hand, dodder can greatly reduce a farmer's harvest or even destroy crops completely. Before sowing their produce, especially farmers in warm parts of the world often check to make sure no unwanted dodder seeds have mixed with their crop seeds. This is a good way to stop dodder plants from making their way to a crop field secretly.

    In the world today, all of the people need recreation(消遣). We cannot work all the time if we are going to keep healthy and enjoy life.

    Everyone has his own way of relaxing. Perhaps the most popular form is to take part in sports. There are team sports, such as basketball and football. There are also individual(个人的) sports, such as swimming and running. Skating and mountain climbing are the most popular recreation for people who like to be outdoor. Not everyone who enjoys sports likes to take part in them. Many people like watching them on TV or listening to them on the radio. So many people like some forms of recreation, such as watching TV, singing and dancing. It doesn't matter whether we like indoor recreation or take part in outdoor sports. It is important for everyone to relax from time to time and enjoy some forms of recreation.

    Since his students began using Quizlet, English teacher Tristan Thorne has noticed an improvement in their ability to learn and use new words. Quizlet is a learning App, a computer program you use on your mobile phone. It can help users build and test their knowledge of English words. Quizlet has word sets for millions of subjects. And, it is quickly becoming a useful mobile tool for language learners.

    Thorne teachers at Columbia University in New York City. Thanks to learning Apps, Jeff Strack, another English teacher, has also notice improvement in his students' ability to remember information. He teaches at Hostos Community College, also in New York. He and Thorne are part of a growing number of language educators adding mobile Apps to their classes.

    Strack and Thorne seem to agree that the days when teachers would not permit the use of mobile phones are gone. When they use Apps, language learners communicate more differently than in a traditional classroom. Users act on or respond to something, instead of just listening to new information.

    Thorne believes that Apps can help learners become more active in learning. For example, each week, his students are required to add vocabulary words into Quizlet for others to use. He says some Apps also make it easy for students to know their language strengths and weaknesses.

    The biggest improvement Strack has seen in his students is that they are much more active inwhole-class or small-group discussions. “Apps let all students take part in the activity, whether it's a game, quiz or practice activity.” he says.

    Many existing learning Apps are designed for students of all ages and levels. Some are designed for group activities. Some support independent learning. Still some are good for homework. Thorne says he especially likes Quizlet and three other Apps: QR Codes, Socrative and Evernote.

    University Room Regulations

    Approved and Prohibited Items

    The following items are approved for use in residential(住宿的)rooms: electric blankets, hair dryers, personal computers, radios, televisions and DVD players. Items that are not allowed in student rooms include: candles, ceiling fans, fireworks, waterbeds, sun lamps and wireless routers. Please note that any prohibited items will be taken away by the Office of Residence Life.

    Access to Residential Rooms

    Students are provided with a combination(组合密码）for their room door locks upon check-in. Do not share your room door lock combination with anyone. The Office of Residence Life may change the door lock combination at any time at the expense of the resident if it is found that the student has shared the combination with others. The fee is ＄25 to change a room combination.

    Cooking Policy

    Students living in buildings that have kitchens are only permitted to cook in the kitchen. Students must clean up after cooking. This is not the responsibility of housekeeping staff. Kitchens that are not kept clean may be closed for use. With the exception of using a small microwave oven（微波炉） to heat food, students are not permitted to cook in their rooms.

    Pet Policy

    No pets except fish are permitted in student rooms. Students who are found with pets, whether visiting or owned by the student, are subject to an initial fine of ＄100 and a continuing fine of ＄50 a day per pet. Students receive written notice when the fine goes into effect. If, one week from the date of written notice, the pet is not removed, the student is referred to the Student Court.

    Quiet Hours

    Residential buildings must maintain an atmosphere that supports the academic mission of the University. Minimum quiet hours in all campus residences are 11:00 pm to 8:00 am Sunday through Thursday. Quiet hours on Friday and Saturday nights are 1:00 am to 8:00 am. Students who violate quiet hours are subject to a fine of ＄25.