C

    Every year, hundreds of millions of Monarch Butterflies(黑脉金斑蝶) from Canada and the United States journey as far as 2, 500 miles to the forests of Michoacan, Mexico, a place which has the world's largest insect migration(迁移). It's such a breathtaking sight, but as always, human greed is threatening to destroy it.

    The Monarch Butterflies start to arrive in Michoacan in late October to make their winter home in the trees high up in the mountains of the natural reserve. Once there, they gather together in large masses. These masses often become so heavy that they cause tree branches to bend or even break. But there's a purpose of all these massing — it allows the butterflies to survive in the low nighttime temperatures at these high altitudes.

    The Michoacan Monarch Butterfly Sanctuary is most impressive during the months of February and March, just before the winged insects begin their long journey home.

    Mexico's Butterfly Forest is a shelter protected by law, and one of the country's most popular sights, but that hasn't stopped people from slowly but steadily destroying it.

    Illegal woodcutting in the heart of the Monarch Butterfly Biosphere Reserve has been a longstanding problem, but criminals are rarely brought to justice. They are often set free after paying some money.

    Just last month, an even greater threat rose in Michoacan's butterfly home.  The country's largest mining corporation gained the right to reopen an old mine in the heart of the monarch reserve. Experts believe that if the mine is reopened, it will likely spell the end of this magical place.

    And as if all this wasn't bad enough, the increasing use of herbicides（除草剂） in the American corn belt has led to the decrease of  a plant which is essential to the monarchs' development from egg into butterfly.

    Almost every night for more than 10 years, Kirk Alexander, 48, ordered a late dinner from his local restaurant Domino's Pizza. But for the past two weeks, he hasn't called for even once.

    “A few of my staff mentioned that we hadn't seen his order in a while. Then I found that it had been 12 days since he last ordered, which is not like him,” Domino's general manager Sarah Fuller said, feeling she could no longer ignore Kirk's recent absence.

    Sarah has known Kirk since 2009, when she started working at the Domino's Pizza as a deliver driver and often made the short trip to Kirk's home about six minutes away. She knew Kirk worked from home, and neighbors said he seldom left. She also knew that he had some health problems in the past. Something, Sarah worried, was wrong.

    Around 1 a.m. on May 8, Sarah sent delivery driver Sean Hamblen to visit Kirk's home. Sean arrived at Kirk's home and knocked on the front door several times. There was no answer. He later noticed that the lights and the TV in the home were on. When he called Kirk's phone, it went straight to voice mail.

    Sean drove back to the restaurant to tell Sarah and they decided to call 911. Soon, officers arrived at Kirk's home. So did Sarah and Sean. They heard a man calling for help from inside. Officers broke down the door and found Kirk on the floor in need of medical attention at once after suffering from a heart attack. One day later, they might have been too late.

    So is keeping an eye on regular customers part of Domino's business plan? Not really. “Kirk is part of our family here and we feel like we need to do something.” Sarah said.

    We all have to make decisions all the time, and we have an abundance of choices, ranging from tiny issues to vital ones. Unfortunately, people often find it hard to make decisions{#blank#}1{#/blank#} If you would like to improve your skill of decision making, here are four suggestions for you. Don't expect to have it all.

    {#blank#}2{#/blank#} You can't order every delicious dish on the menu. And there will be paths not taken, careers not chosen, to name a few. You can imagine some “what if' situations if you must, but do not let them take up too much space in your brain.

    {#blank#}3{#/blank#}

    It's often good to think through your decisions. But don't overdo it. Research can reach a point where returns begin to reduce, which makes it confusing more than clarifying. Many good decisions can be made based as much on intuition (直觉) as on careful assessment of endless data.

    Don't delay making decisions.

    Yes, there is a time to put off making a decision. Perhaps you need more information{#blank#}4{#/blank#} Or it's likely that you wait for a less stressful time. Just don't wait so long that the decision is made by your own indecisiveness.

    Don't be hard on yourself.

    You decide to go on a voyage. You choose an expensive liner. Everything should work out just right. Only you didn't expect a bug that ran around on the ship, making you and your family sick for five days{#blank#}5{#/blank#}But please remember it is unavoidable sometimes.

A. Don't spend too much time thinking.

B. It is an important source of information.

C. Don't count on emotion to make decisions.

D. Maybe you wish to consult with your advisor.

E. You may regret making such a stupid decision.

F. That means the skill of good decision-making counts a lot.

G. Decisions force us to close the door on other possibilities.

    A new study suggests climate conditions in the Sahara Desert, one of hottest, driest and most deserted areas in the world, have changed from wet to dry a about every 20,000 years.

    But previous evidence has suggested the Sahara did not always experience such extreme heat and dry conditions. At times, the Sahara Ranged to a very wet climate. This permitted plants and animals to develop and grow and led to the creation of human settlements. Now, they have discovered more evidence, which, the lead researcher David Mc Gee says, supports the idea that the Sahara's climate kept changing between wet and dry about every 20,000, years.

    McGee reported these climate changes were mainly driven by changes in the Earth's(地轴)as the planet travels round the sun .This process affects the amount of sunlight between seasons. Every 20,000 years the Earth receives more strong summer sunlight. When the Earth's axis changes again, the amount of sunlight is reduced. This season change happened continuously every 20,000 years. The other part of the season produced rainy conditions, resulting in a wetter, greener, plant-rich environment. When the rainy activity weakens, the climate becomes hot and dry, like the Sahara remains today.

    The scientists based their research on dust collected from ocean sediment(沉积物)in the Atlantic Ocean bottom off the coast of West Africa. The dust contained layers (层)of ancient sediment built up over millions of years. Each layer could contain traces of Saharan dust as well as the remains of life forms. This information was used to assess over what time period the dust had built up. This led to the overall finding that the Saharan changes from wet to dry climates happened every 20,000 years.

David McGee said that today we only see the Sahara Desert as an extremely deserted and "inhospitable" place. The new study suggests that the area's climate has changes between grasslands and a much wetter environment, and back to dry climates, even over the last quarter million years. McGee says he thinks the latest research can be valuable in studying the Sahara's history as it relates to human settlement.

    Are you familiar with the greeting, "Can I add you on WeChat?" It seems like every time we meet new friends or colleagues nowadays, the first thing that springs to mind is adding each other on the app. Nevertheless, more than 80 percent of WeChat users report feeling stressed or anxious when they receive a large number of messages, according to a study done recently by the app's developer Tencent(腾讯). In other words, WeChat can overwhelm(使应接不暇) us, while also breaking down the boundaries between our work and private lives.

    Just think how easy it is now for bosses to hand out assignments during the holiday, so long as they have your WeChat contact. When you're at the cinema enjoying a romantic movie or having a barbecue in the backyard, you can never cut yourself off from the outside world unless you switch off your phone. Not to post something in WeChat Moments before replying to your boss first!

    Apart from interrupting your leisure time, WeChat can also reduce your productivity at work. For many office workers, logging in to WeChat on their computers at the start of the day has become routine. But what if browsing the Moments distracts us from doing the work? The app steals our time without us even noticing it, making us have the false belief that we are busy all the time.

    And as if that weren't bad enough, there're the "one-off" friends who take up space on our WeChat friend list. A handy way to check how many one-off friends you have is to take a look at your chat history with them. Sometimes, you only sent the initial friend requests so you could invite them to a WeChat group or inform them of something for your boss. Yet still, as your friend count(好友数量) ever goes up, it can make you feel the need to post selfies(自拍) and share details of your life in your Moments, just so you can stay up to date.

    With WeChat, all our spare time is swallowed up by the constant torrent of messages and our attention keeps getting diverted by Moments and pop-up ads. So it's time that we should do something to nip this problem in the bud.

    An experimental cleanup device called RemoveDEBRIS has successfully cast a net around a dummy (仿真的) satellite, imitating a technique that could one day collect spaceborne garbage.

    The test, which was carried out this week, is widely believed to be the first successful demonstration of space cleanup technology, experts told CNN. And it symbolizes an early step toward solving what has already been a critical issue: junk in space.

    Millions of pieces of junk are turning around in orbit the result of 50 years of space travel and few regulations to keep space clean. At orbital speeds, even a small bit of paint crashing with a satellite can cause critical damage.

    Various companies have plans to send thousands of new satellites into low-Earth orbit, already the most crowded area.

    The RemoveDEBRIS experiment is run by a company and researchers led by the U. K.'s Surrey Space Center and includes Airbus, Airbus-owned Surrey Satellite Technology Ltd. and France's ArianeGroup.

    Guglielmo Aglietti, the director of Surrey Space Center, said that an operational version of the RemoveDEBRlS technology would cast a net that remains fastened to the main satellite so the debris can be dragged out of orbit. It could target large pieces of junk, including dead satellites up to 10 meters long.

    The RemoveDEBRIS satellite will conduct a few more experiments in the coming months, including testing navigation features that could help guide the satellite to a specific piece of debris.

Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, said the success of this week's experiment was exciting, but he cautioned against "over- publicizing" it.

    There are still enormous barriers to clear before operational cleanup tasks are underway, he said, and the most discouraging is figuring out how to fund such projects.

    Aglietti, the Surrey professor who helped lead the RemoveDEBRIS project, said "The challenge will lie in persuading the relevant authorities to sponsor these tasks." Aglietti said he hopes RemoveDEBRIS will conduct a few cleanup tasks per year, targeting the largest pieces of junk in the most crowded orbits.