How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets, and thousands of stars.
But scientists believe there are some things in the sky that we will never see. We won’t see them with the biggest telescope (望远镜) in the world, on the clearest night of the year. That’s because they are invisible (看不见的). They’re the mysterious dead stars called black holes.
You might find it hard to imagine that stars die. After all, our Sun is a star. Year after year we see up in the sky, burning brightly, giving us heat and light. The Sun certainly doesn’t seem to be getting old or weak. But stars do burn out and die after billions of years.
As a star’s gases burn, they give off light and heat. But when the gases run out, the star stops burning and begins to die.
As the star cools, the outer parts of the star pull in toward the center. The star is squashed (挤压) into a smaller and smaller ball. If the star was very small, the star ends up as a cold, dark ball. If the star was very big, it keeps being squashed inward until it’s packed together tighter (紧的) than anything in the universe.
Imagine if the Earth collapsed until it was the size of a tiny marble (玻璃球). That’s how tightly this dead star, a black hole, is packed. What pulls the star in toward its center with such power? It is the same force that pulls you down when you jump – the force call gravity. A black hole is so tightly packed that its gravity absorbs everything – even light. The light from a black hole can never come back to your eyes. That’s why you see nothing but blackness.
So the next time you look up at the night sky, remember: there’s more in the sky than meets the eye! Scattered (散落) in the silent darkness are black holes – the great mystery of space.
1. What might happen after a star dies?| A．The star might become a black hole. | B．The Earth might be hit by the star. |
| C．The sky might become much darker. | D．The gravity might totally disappear. |
| A．Its gases run out. | B．It hits other stars. |
| C．It gets too hot. | D．Its light fades away. |
| A．Rolled. | B．Ran. | C．Fell inward. | D．Spread out. |
| A．Most black holes are too far away. | B．We don’t have a powerful enough telescope. |
| C．Black holes can travel as fast as light. | D．Light can not escape a black hole’s gravity. |
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【推荐1】When you think of a robot, what do you see? A machine that looks a bit like you and me?
What a robot looks like depends on its purpose. Cleaning robots often look like little vacuums.
Whether they look like us or not, most robots have three essential parts that make them a robot: sensors, actuators and programs.
Together, these parts are what make a robot different from other gadgets you might have around your house, like your computer or your washing machine.
Second, a robot has actuators that allow it to move around.
Third, a robot needs a program that lets it act on its own based on what it is sensing.
| A．Flying robots might have wings like birds. |
| B．The past robots were not artificially intelligent. |
| C．We might use our legs and feet to walk and run. |
| D．This ability to act on one’s own is called autonomy. |
| E．First, a robot has sensors that allow it to “see” the world. |
| F．We would need some actuators so that the robot could move. |
| G．The reality is that robots can have different shapes and sizes. |
【推荐2】The poet Lovelle Drachman once said, “blessed are the curious, for they shall have adventures.”, which is certainly true of people with wanderlust.
“Wanderlust” is derived from a German word meaning “a love of hiking” and now used to describe the burning desire to escape the everyday and explore the unfamiliar. Wanderlust is a common, but not universal experience. What makes some people catch that travel bug while others are apparently unaffected?
One theory is to do with our genes. Scientific research has identified a variant of the DRD4 gene that affects sensitivity to dopamine (多巴胺), the neuro-transmitter often released in the brain when we do something we enjoy. Actually, it’s not that the 7R version of the DRD4 specifically creates a thirst for travel, but people with the 7R variant are less sensitive to that delicious dopamine hit.
So simple things that bring other people pleasure, like a jog in the park or a cheeky chocolate treat, might not cut it for them, which makes those with the 7R type of the DRD4 gene more likely to be risk takers to get increased dopamine levels. That’s way DRD4-7R has been called the wanderlust gene. Other researches have also linked the same 7R variant to far riskier behaviours, such as addiction and offensive behaviour. By comparison, the strong sudden desire to go travelling seems like the better end of the Theory of Evolution.
But another theory looks at the psychology of living in our inter-connected human society, one in which we are constantly aware of what friends and social media influencers are doing and keep comparing ourselves to them in two distinct ways. Upwards social comparisons, comparing ourselves to those we see as more successful than us. And downward social comparisons, comparing ourselves to those we see as worse off than us. In the age of social media, it’s very easy to compare ourselves unfavourably with the idealized version. How can we compete with influencers, with their perfectly dark brown legs on neat and clean while sand, and their once in a lifetime sunsets over Machu Picchu?
Whether the motivation to explore the world is genetic, psychological or something else, there are far more harmful hobbies than the desire to explore the world. Venturing outside your comfort zone, to learn about new cultures, meet people you might otherwise never have had the chance to meet, and finally, learn who you are in different situations. Sounds like a life well-lived. As the novelist Jack Kerouac said, “Because in the end, you won’t remember the time you spent in the office or mowing your lawn. Climb that goddamn mountain.”
1. The underlined phrase “catch that travel bug” in Paragraph 2 is closest in meaning to _______.| A．be crazy about travelling | B．be curious about travelling |
| C．escape daily life by travelling | D．experience common travelling |
| A．Because they are more fascinated by risks and unfamiliar things. |
| B．Because the 7R variant cause them to be less sensitive do dopamine hit. |
| C．Because they have comparatively higher level of dopamine than other people. |
| D．Because the 7R variant, also called wanderlust gene, helps create a craving for travelling. |
| A．a well-lived life doesn’t involve venturing outside comfortable zone |
| B．the 7R variant is inevitably linked with some more risky behavior such as addiction |
| C．people tend to forget their daily routine, but adventures really leave footprints in their hearts |
| D．when people compare themselves with less successful ones, it may give rise to mixed feelings |
| A．Wanderlust and its two main categories. |
| B．A less harmful hobby and analysis of its different cause. |
| C．The distinctions between gene variants and social comparisons. |
| D．Physical and psychological reasons for the desire to explore the world. |
【推荐3】The space community is taking the orbital debris (碎片) threat increasingly seriously these days. Multiple satellite “mega-constellations (巨型星座)” are in the works, making space traffic management and space-junk removal more pressing issues than they’ve ever been.
For instance, SpaceX has already launched more than 1,700 satellites for its Starlink broadband constellation. The company ultimately wants to launch around 30,000Starlink satellites into orbit. One Web has launched more than half of the satellites for its planned 648-member constellation, which may also grow beyond that initial number as time goes on.
In addition, satellite construction costs continue to fall, allowing more and more people to get satellites up and operate them—including folks with very little experience in the field. This opening of the final frontier is generally a good thing, but it further highlights the need for responsible action when it comes to satellite operation. In 2019, for example, the Space Safety Coalition (SSC) laid out a set of proposed voluntary guidelines designed to control space junk over the coming years.
One recommendation is that all satellites operating above 250 miles be equipped with propulsion(推进) systems, allowing them to get away from possible collisions (碰撞). The SSC also recommends operators who control satellites in low Earth orbit should include in their launch contracts a requirement that rocket upper stages should be got rid of in the atmosphere shortly after liftoff.
More active debris-fighting strategies could also be part of the solution. Removing just a handful of rocket bodies or dead satellites every year could help us keep our space-junk problem under control, according to some studies. And researchers around the world are developing and testing ways to do just that, using nets, harpoons(鱼叉) and other methods.
The space-junk issue is a global one, so governments around the world should have conversations about how to deal with it. Let’s hope the talks, the decisions and the tech end up outpacing the problem.
1. What do the two examples in Paragraph 2 illustrate?| A．Orbital debris ensure satellite safety. |
| B．Constellations consist of many satellites. |
| C．Space is becoming increasingly crowded. |
| D．SpaceX has higher capacity to explore space. |
| A．Experience in this area is rich. |
| B．Satellites are cheaper to make. |
| C．Satellite operations require little skills. |
| D．Space is accessible to common people. |
| A．Remove dead satellites from orbit. |
| B．Cooperate in monitoring satellites. |
| C．Operate satellites at a fixed height. |
| D．Recycle a rocket shortly after liftoff. |
| A．Space junk cleanup |
| B．The risks of space junk |
| C．Space debris and satellites |
| D．Guidelines for space safety |
【推荐1】Twelve wants to make a great number of products greener by changing where the carbon used in their production comes from — taking it from carbon dioxide caught in the air instead of from the ground in the form of fossil fuels. “If we can take the basic carbon molecule (分子) and put new elements around it, in that case, it can be useful in industry,” says co-founder Etosha Cave, “we can basically shift what’s happening with our atmosphere and what’s happening with climate change.” Or, as her fellow co-founder Kendra Kuhl puts it: “Changing carbon changes everything.”
To achieve this transformation (转变), the company created a catalyst, something that breaks down carbon dioxide caught from the air into smaller atomic bits, such as carbon and oxygen, using water and electricity to recombine the elements and for mother carbon compounds (混合物) that make up the basis of a wide range of chemicals and fuels.
Twelve’s carbon transformation system can be added to existing producing processes and it send products used as a direct replacement for standard petrochemicals. That allows other companies to cut their dependence on fossil fuels in production.
“By sourcing carbon from carbon dioxide instead of fossil fuels, we can largely reduce our emissions (排放) while keeping the products we know and love,” says Cave. Brands are taking note. Twelve’s chemicals are currently being used to produce Mercedes-Benz car parts, a line of Pangaia sunglasses and soon.
Twelve also created his own sustainable (可持续的) fuels, E-Jet and E-Marine, which are used to power aircraft and ships.
1. What allows Twelve to make greener products?| A．Taking carbon from the air. |
| B．Transforming the forms of fossil fuels. |
| C．Fixing the climate and atmosphere problems. |
| D．Planting more trees for new chemical elements. |
| A．Preparing water and electricity. |
| B．Collecting carbon dioxide from the air. |
| C．Separating carbon dioxide into smaller parts. |
| D．Rejoining elements like carbon and oxygen for the mixture. |
| A．Reducing the costs of their products. |
| B．Making them better known to the world. |
| C．Being less dependent on fossil fuels than ever. |
| D．Creating more sustainable fuels for other fields. |
| A．Twelve’s Great Achievements | B．Green House Effect |
| C．Carbon Transformation System | D．Limitations of Fossil Fuels |
【推荐2】There’re some important days to remember in April.
First Modern Olympics
On April 6, 1896, King George Ⅰ of Greece welcomed people to take part in the Summer Olympic Games in Athens.
Back then, Athens was just a small village, and news about the Games was unable to reach many people. As a result, only 245 athletes took part in the games. They weren’t chosen by their countries like now. Instead, they came by themselves and paid for the journey themselves. Ever since then, the Summer Olympic Games have been held every four years in a different city around the world.
World Health Day
April 7 is World Health Day. This day is not just about hand washing and healthy eating. Each year a different theme is selected. For example, the theme of 2012 World Health Day was Ageing and Health.
In 2018, World Health Day focused on high blood pressure. The main causes of blood pressure include stress, too much salt in your food and too little exercise.
World Earth Day
We call the Earth our “mother”. However, our “mother” is facing lots of problems. April 22 is designated (指定) as World Earth Day. It’s a day to remind us to care about the planet. On this day people do things to help improve the environment and cut down their energy use. World Earth Day comes only once a year, but it reminds people to live in a green way every day. If we truly care about the planet, everyday can be Earth Day!
1. Why did only 245 athletes take part in the first Olympic Games?| A．Because most people weren’t interested in it. |
| B．Because communication wasn’t developed. |
| C．Because King George Ⅰ didn’t allow the news to be spread. |
| D．Because the journey to Athens was too long and expensive. |
| A．Too much work. | B．Too much stress. |
| C．Too little exercise. | D．Too much salt. |
| A．To ask us to respect the tradition. | B．To tell us some important days in April. |
| C．To ask us to protect the environment. | D．To tell us how to celebrate those days. |
【推荐3】It’s school time again! You’re probably feeling excited and maybe a little sad that summer is over. Some kids feel nervous or a little scared on the first day of school because of all the new things: new teachers, new friends, and even a new school. Luckily, these “new” worries only stick around for a little while. Let’s find out more about going to a new school.
Most teachers kick off the new school year by introducing themselves and talking about all the stuff you’ll be doing that year. Some teachers give students a chance to tell something about themselves to the rest of the class, too. When teachers do the talking on the first day, they often go over classroom rules and school rules so you’ll know what’s allowed and what’s not. Please pay close attention.
You might already know a lot of people in your classes on the first day, but it’s a great day to make a new friend, so try to say hello to kids you know and new ones that you don’t. Make the first move and you’ll be glad you did, and so will your new friend!
Seeing friends you haven’t seen for some time can make the first day a good one. You can make the day feel special by wearing clothes that you really like. Maybe you got a great T-shirt on one of your vacations, or a pair of sneakers (运动鞋). It also can make you feel good to be prepared and have all the things you need, such as pencils, folders, and whatever else you’ll be needing. But make sure that you pack them the night before in case you don’t have time in the morning.
1. The underlined phrase “kick off” in the second paragraph probably means “________”.| A．start | B．study | C．find | D．learn |
| A．what to know about a new school | B．how to prepare for a new school |
| C．what to do on your first day of school | D．how to spend your first day of school |
| A．introduce yourself | B．learn about the school rules |
| C．make new friends | D．go over your lessons |
| A．nervous | B．mad | C．happy | D．upset |
