Divide the bills evenly. Some studentsare far less responsible than their roommates and tend to let their part of thefinance slide. Dissatisfaction is quick to build when everyone has to pay thebill for a fellow student who can't seem to pay his/her share of the money.

    Carry your part of the load. Everyonehas to clean the bathroom and the kitchen sometime. Don't avoid your part ofresponsibility. Student accommodations can get messy and it involves everyoneto keep them tidy and healthy.

    Think about someone else before youthink about yourself. Put your roommates interests above your own. Life will befar enjoyable when everyone is concerned about the feelings property andstudies of each other.

    Be open and honest. Hostilities (敌意) andfrustrations may cause problems that can't be fixed. Everyone brings differentstandards and expectations to group living and it's in everyone's best interestto put them into the open. Disagreements can be managed more warmly when your arewilling to be both open and listen to others.

    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.

    Today is National Bike-to-Work Day. And on New York City's jammed streets, people are cycling on hundreds of miles of new bike lanes. But New York's widespread efforts to make streets safer for bikes have also left some locals complaining about the loss of parking spots and lanes for cars.

    When the weather is good, Aaron Naparstek likes to pedal（用踏板踩） his two young kids to school on a special Dutch-made bicycle. Naparstek supports the new lane.

    Aaron: The bike lane on Prospect Park West is really introducing a lot of new people to the idea that it's possible to use a bike in New York City for transportation or to travel around. This is what 21^st century New York City looks like.

    Prospect Park West is still a one-way road, but where it used to have three lanes of car traffic, now it has two, plus a protected bike lane. Supporters say that makes the road safer for everyone, including pedestrians, by slowing down cars and taking bikes off the sidewalk. But some longtime residents disagree. Lois Carswell is president of a group called Seniors for Safety. She says the two-way bike lane is dangerous to older residents who are used to one-way traffic.

    Lois: We wanted a lane — the right kind of lane that would keep everybody safe, that would keep the bikers safe. But we want it to be done the right way. And it has not been done the right way.

    Craig Palmer builds bars and restaurants in Manhattan. I was interviewing him for a different story when he brought up the bike lanes all on his own.

    Craig: I think the biggest problem is that Bloomberg put all these bike lanes in. You took what used to be a full street and you're shrinking it.

    Then there are the Hasidic Jews in Williamsburg, Brooklyn, who forced the city to remove a bike lane through their neighborhood. But polls show that the majority of New Yorkers support bike lanes by a margin of 56% to 39%. Bicycle advocate Caroline Samponaro of Transportation Alternatives calls that a mandate.

    Caroline: If this was an election, we would have already had our victory. The public has spoken and they keep speaking. And I think, more importantly, the public is starting to vote with their pedals.

    It was an autumn morning shortly after my husband and I moved into our first house. Our children were upstairs unpacking, and I was looking out of the window at my father moving around mysteriously on the front lawn. “What are you doing out there?” I called to him.

    He looked up, smiling. “I'm making you a surprise.'' I thought it could be just about anything. When we were kids, he always created something surprising for us. Today, however, Dad would say no more, and caught up in the business of our new life, I eventually forgot about his surprise.

    Until one gloomy day the next March when I glanced out of the window, I saw a dot of blue across the yard. I headed outside for a closer look. They were crocuses (番红花) throughout the front lawn—blue, yellow and my favorite pink, with little faces moving up and down in the cold wind. I remembered the things Dad secretly planted last autumn. He knew how the darkness and dullness of winter always got me down. What could have been more perfectly timely to my needs?

    My father's crocuses bloomed (开花) each spring for the next five seasons, always bringing the same assurance: Hard times are almost over. Hold on, keep going, and light is coming soon.

    Then a spring came with only half the usual blooms and the next spring there were none. I missed the crocuses, so I would ask Dad to come over and plant new bulbs (块茎植物). But I never did. He died suddenly one October day. My family were in deep sorrow, leaning on our faith.

    On a spring afternoon four years later, I was driving back when I felt depressed. It was Dad's birthday, and I found myself thinking about him. This was not unusual-my family often talked about him, remembering how he lived up to his faith. Suddenly I slowed as I turned into our driveway. I stopped and stared at the lawn. There on the muddy grass with small piles of melting snow, bravely waving in the wind, was one pink crocus.

    How could a flower bloom from a bulb more than 18 years ago, one that hadn't bloomed in over a decade? But there was the crocus. Tears filled my eyes as I realized its significance.

    Hold on, keep going, and light is coming soon. The pink crocus bloomed for only a day, but it built my faith for a lifetime.

    As scientists in the Netherlands tried to figure out how to build a super flying robot, they learned from one of nature s flyers: the humble fruit fly(果蝇).And by building this robot, they've gained new insights into how the fly carries out one of its dangerous tasks.

    The robot is called the DelFly Nimble Its wingspan(冀展)is about a foot wide. It has four wings that can beat at 17 times per second, which appear very delicate because they're made of the same material as space blankets.

    In the previous designs, they always had a tail, like a traditional airplane tail, said the robots main designer Matej Karasek. He's based at the Micro Air Vehicle Laboratory at Delft University of Technology in the Netherlands, and he and his colleagues published their findings on Thursday in Science

    “In the previous generations", he said, "flapping wings drove the robot forward while the tail helped to guide and stabilize it. But now the DelFly Nimble is completely controlled by the wings. The challenge then was actually combine the control into the wing movement, and that's what we achieved, Karasek said

    In the latest generation. the wings can each move individually or rotate(旋转)around the body of the robot in order to maximize the machine s agility(灵活 ) The robot can remain in one place in the air for about five minutes on a full battery or fly for more than a kilometer"， Karasek said, "And because the scientists are controlling all the movements, they can use the robot to learn more about how fruit flies actually carry out their dangerous tasks, which has caught the attention of biologists.”

    On April 2, we said goodbye to Tiangong I, China's first space lab. According to the China Manned Space Agency（中国载人航天）, Tiangong I re-entered the Earth's atmosphere （大气层）and fell into the South Pacific Ocean.

    There are many spacecraft that are still in orbit above the Earth. They are flying at heights ranging from 300 to 1,000 kilometers. After finishing their trips, they will all re-enter the Earth's atmosphere like Tiangong I.

    There are two types of re-entries：controlled（受控的）re-entry and uncontrolled re-entry.

    Some satellites（卫星）and manned spacecraft come back to the Earth in a controlled re-entry. Scientists calculate（计算）the path of the falling spacecraft and its speed. They can guide the spacecraft to fall in a chosen area. In 2017,Tianzhou I, China's first cargo（货运）spacecraft, was directed to fall in the South Pacific Ocean.

    Some spacecraft may have problems while in space, or are simply no longer usable after a certain amount of time.  These craft come back in an uncontrolled re-entry.  It is hard to tell when and where these spacecraft will fall until the last few hours. The US space station Skylab came back partially uncontrolled in 1979. Parts of the station fell in western Australia, but no one was injured.

    During re-entry, most of the spacecraft will burn up while passing through the Earth's atmosphere. Only a small amount of the debris（碎片）will reach the ground.

    The debris typically ends up falling into the ocean, China Daily reported. Tiangong I weighs about 8.5tons. The amount of debris that falls to the Earth might be about 1 to 1.5 tons, the Beijing News reported.  That is about the same weight as a car.