1 . It is hard to imagine that plants or animals could ever exist on Mars. But scientists continue to look for evidence. NASA, America’s space agency, has found evidence that, a long time ago, there was surface water on the Mars. Scientists believe water is necessary for life as we know it. So since that discovery, they have been looking for chemicals that would be present if there once was or still is life on the planet.
At a December 13 meeting in California, NASA scientists reported an important discovery on Mars. They said for the first time that they had found very small amounts of boron(硼). Boron is important because it could help build RNA molecules(分子). And RNA molecules are important because they are one of the basic building parts for life.
One of the next steps in the scientists’ search for life on Mars comes soon. The next spacecraft is planned to launch. It will bring rocks from Mars back to Earth. Scientists in Britain are getting ready for those Mars rocks now. Before this, using a powerful microscope(显微镜), they have already examined 200-million-year-old volcanic rocks found deep in the Pacific Ocean. The microscope showed holes on the rocks caused by tiny living things called microbes(微生物). Microbes are the oldest form of life on Earth.
Next, the scientists in Britain will examine rocks which contain ancient material from Mars. The material comes from a time when Mars would have been more likely to support life. The scientists hope to get the same findings in the rocks from Mars as the ones they saw in the ocean rocks. If they do, they predict that the rocks coming directly from Mars will also show signs of life. That, in turn, could finally prove that we are not alone in the universe.
1. What caused scientists to look for evidence of life on Mars?| A．The discovery of plants. | B．The discovery of chemicals. |
| C．The discovery of surface water. | D．The discovery of RNA molecules. |
| A．It is hardly seen on the earth. | B．It might prove the existence of life. |
| C．It might cause the holes on the rocks. | D．It is the most necessary part of life. |
| A．Tiny living things. | B．Ancient material from Mars. |
| C．Volcanic rocks. | D．Holes caused by microbes. |
| A．Scientists Try To Look For Life On Mars |
| B．Does Surface Water Really Exist On Mars? |
| C．A Discovery Of Life In The Pacific Ocean |
| D．Boron-An Important Chemical Supporting Life |
2 . In a former gold mine a mile underground, inside a titanium tank(钛储罐)filled with a rare liquified gas, scientists have begun the search for what so far has been unfindable: dark matter.
Scientists are trying to understand why the universe is not what it seems. One part of the mystery is dark matter, which has by far most of the mass in the universe. Astronomers know it’s there even though it’s nowhere to be seen, because when they measure the stars and other regular matter in galaxies, they find that there is not nearly enough gravity to hold them together. If nothing else was out there, galaxies would be quickly flying apart.
The race to solve this enormous mystery has brought one team to the depths under Lead, South Dakota.
The idea is that a mile of dirt and rock, a giant tank, a second tank and the purest titanium in the world will block nearly all the cosmic rays and particles (粒子) around us every day. But dark matter particles, scientists think, can avoid all those obstacles. They hope one will fly into the liquid xenon (疝气) in the inner tank and smash into a xenon nucleus (原子核), revealing its existence in a flash of light seen by a device called “the time projection chamber.”
Scientists announced Thursday that the five-year, $60 million search finally got underway two months ago after a delay caused by the pandemic. So far the device has found...nothing. At least no dark matter.
And if all their calculations and theories are right, they figure they’ll see only a couple signs of dark matter a year. By the time the experiment finishes, the chance of finding dark matter with this device is probably less than 50% but more than 10%.
While that’s far from a sure thing, “you need a little enthusiasm,” said Kevin Lesko, a physicist at Lawrence Berkeley Naonal Laboratory. “You don’t go into rare search physics without some hope of finding something.”
These scientists tried to a similar, smaller experiment here years ago. After coming up empty, they figured they had to go much bigger. Another large-scale experiment is underway in Italy run by a rival team, but no results have been announced so far.
1. What do we know about dark matter?| A．It is a rare liquified gas. |
| B．It is invisible and hard to find. |
| C．It is unknown to scientists. |
| D．It is a form of gravity in the galaxies. |
| A．The result of the experiment. |
| B．The design of the experiment. |
| C．The reason for conducting the experiment. |
| D．The importance of the experiment. |
| A．Its success is guaranteed. |
| B．It is almost finished. |
| C．It has been fruitless so far. |
| D．It is the first attempt in the field. |
| A．Don’t count your chickens. |
| B．Two heads are better than one. |
| C．Strike while the iron is hot. |
| D．Every cloud has a silver lining. |
3 . It took humans thousands of years to understand our own planet, and centuries
Up to the present time, astronomers have
Among all these, scientists are eager to find a clue of the
| A．explore | B．separate | C．forget | D．defend |
| A．revised | B．discovered | C．saved | D．created |
| A．travelled | B．damaged | C．recognized | D．ignored |
| A．slowly | B．easily | C．wrongly | D．rapidly |
| A．Removing | B．Circling | C．Lighting | D．Showing |
| A．stars | B．moons | C．planets | D．satellites |
| A．type | B．distance | C．power | D．size |
| A．authorities | B．species | C．systems | D．facilities |
| A．familiar | B．previous | C．unknown | D．distant |
| A．hide | B．discover | C．injure | D．support |
| A．luckily | B．instantly | C．probably | D．officially |
| A．small | B．bright | C．blue | D．clear |
| A．And | B．Yet | C．So | D．Thus |
| A．limits | B．ends | C．opposites | D．beginnings |
| A．examples | B．designs | C．means | D．signs |
4 . A new study focuses on K2-18b, an exoplanet(系外行星) discovered in 2018, which orbits a red dwarf star close enough to receive about the same amount of radiation from its star as Earth does from our sun.
Recently, scientists have discovered gas giants that have water in their atmospheres, but this is the least giant planet ever to have water detected in its atmosphere. “The water detection was quite clear to us relatively early on,” lead author Bjorn Benneke, a professor at the Institute for Research on Exoplanets at the Universite de Montreal, told Space.com in an interview.
“Studies have suggested that planets with hydrogen-rich atmospheres could host certain forms of life.” Benneke said. However, “K2-18b’s large atmosphere is extremely thick and creates high-pressure conditions, which likely prevents life as we know it from existing on the planet’s surface.” a news release reads. While these researchers found evidence for liquid water clouds on K2-18b, because of its lack of surface, rain wouldn’t pool on the planet. Without a real surface, so to speak, landing on the planet would also be nearly impossible to land on, especially because the gas is so thick and has such an incredibly high pressure that any Earth-created spacecraft sent there would be destroyed.
Benneke suggests that, possibly, this planet formed by rock absorbing large amounts of gas, “like a vacuum cleaner,” he said. The gas absorbed would have more than doubled the planet and increased its volume Warren eightfood.
To come to these conclusions, the research team analyzed data from Hubble Space Telescope observations that they made between 2019 and 2020 of the K2-18b planet passing in front of its star eight times. This type of research, Benneke said, is leading toward a final goal of “being able to study real, true earth-like planets.” We are not quite there yet, he said, but this is really exciting.”
1. Why is it impossible to land on the K2-18b?| A．It has thin gas. | B．It doesn’t have a real surface. |
| C．It has too much water. | D．It is too far from the earth. |
| A．By releasing gas itself. | B．By receiving radiation from the sun. |
| C．By taking in much gas by rocks. | D．By getting away from the red dwarf star. |
| A．Scientists are making progress in studying real earth-like planets. |
| B．It is impossible for humans to land on other earth-like planets. |
| C．Scientists have succeeded in exploring K2-18b completely. |
| D．The K2-18b planet has passed before its star eight times between 2019 and 2020. |
| A．The exploration of the outer space. |
| B．The study of solar systems’ environment. |
| C．The discovery of the K2-18b planet. |
| D．The research on the K2-18b planet. |
5 . “We are running out of space and the only places to go to are other worlds.... Spreading out may be the only thing that saves us from ourselves. I am convinced that humans need to leave Earth.” These are the words of the famous scientist Stephen Hawking, spoken at a science festival in Norway in 2017, a year before his death.
Hawking was not alone in this view. Many experts feel that the only way for humanity to last far into the future is to colonize （移民） other planets. That way, if an asteroid （小行星）, a terrible disease, nuclear war, or some other disaster strikes Earth, civilization would still have a chance. Mars is one of the ideal destinations. NASA, SpaceX, and Mars One all have plans to send humans there. “Either we spread Earth to other planets, or we risk going extinct,” SpaceX founder Elon Musk said at a conference in 2013.
But not everyone agrees that colonizing Mars or any other planet is such a great plan. The most common argument against going is that it’s just too expensive or dangerous. It will take huge amounts of money and other resources just to get people there, let alone set up a place for them to live. It’s not even clear if humans could survive on Mars.
Maybe all the time and money people would pour into a Mars mission would be better spent on more urgent projects here on Earth, like dealing with poverty or climate change. Some experts argue that handling a problem like an asteroid strike or disease outbreak while staying here on Earth would be much easier and less expensive than surviving on a new planet.
In addition, moving to a new planet could harm or destroy anything that already lives there. Human visitors change or damage the Martian environment. Some feel that’s too much of a risk to take.
1. What is Stephen Hawking’s view according to paragraph 1?| A．The earth is likely to blow up. |
| B．Humans are using up natural resources on Earth. |
| C．It is necessary to spread out to other planets. |
| D．We should explore our world to save ourselves. |
| A．Because there will be a nuclear war in the near future. |
| B．Because human can live better on Mars. |
| C．Because it is a way for earth civilization to last. |
| D．Because it is a way to test our space technology. |
| A．It is wiser to deal with problems on Earth. |
| B．It is easy to stop a disease outbreak. |
| C．Human will not survive on Mars. |
| D．It is impossible to set up a place for people to live on Mars. |
| A．Leaving Earth to Other Planets | B．Should We Colonize Mars? |
| C．New Home on New Planet | D．A Mar Mission Is on The Way |
6 . Shining just 12 light-years from Earth, the star Tau Ceti so resembles the sun that it has appeared in numerous science- fiction stories and was the first star astronomers ever searched for signs of intelligent life, half a century ago. In 2012 Tau Ceti grew still more interesting when astronomers reported five possible planets somewhat larger than Earth circling closer to the star than Mars orbits (围绕……运动) the sun—one of which is in the star’s habitable zone. Newly released images taken by the Herschel Space Observatory provide even more insight about Tau Ceti’s solar system: greater detail about its dust belt.
Dust arises when asteroids and comets (小行星和彗星) crash into one another, so its location reveals where these dust- creating objects—which are too small to be seen directly—orbit a star. In Tau Ceti’s case, “it’s quite a wide dust belt,” says Samantha Lawler of the University of Victoria in British Columbia. As her team reported in November, the belt’s inner edge is roughly two to three astronomical units (AUs) from the star, which is the position of our own sun’s asteroid belt. (An AU is the distance from Earth to the sun.) Tau Ceti’s dust belt extends out to 55 AU, which would be just beyond our system’s main Edgeworth-Kuiper belt, the zone of small bodies whose largest member is probably Pluto. Presumably full of asteroids and comets, Tau Ceti’s dust belt most likely lacks a planet as large as Jupiter, Lawler says. The gravity of such a massive planet would have driven away most small space rocks.
Within a year a new series of radio telescopes in Chile called ALMA should provide a sharper view of the disk, especially of its inner edge. The ALMA images will help astronomers confirm whether the star’s five proposed planets are indeed real. If the disk overlaps the planets’ hypothesized (假设的) orbits, then they probably do not exist; they would have kept away most asteroids near the star, removing the source of dust.
If those planets do exist, however, Lawler’s team suggests that Tau Ceti’s planetary system may resemble what our solar system would have looked like had the four giant planets—Jupiter, Saturn, Uranus and Neptune- never formed: small planets orbiting close to the star, and nothing but asteroids, comets and dust beyond.
1. According to astronomers, the five possible planets of Tau Ceti________.| A．resembled Earth in size |
| B．functioned like a solar system |
| C．were located in Tau Ceti’s habitable zone |
| D．were nearer to Tau Ceti than Mars to the sun |
| A．It is narrower than the asteroid belt in our system. |
| B．The bodies inside it are all smaller than Jupiter. |
| C．The gravity of Tau Ceti makes it get denser. |
| D．It is over 55 astronomical units in width. |
| A．they don’t move into the dust belt while orbiting Tau Ceti |
| B．they have kept away most asteroids and comets |
| C．they don’t crash into any asteroid or comet |
| D．they can be seen clearly by ALMA |
| A．is useful because it stops asteroids or comets crashing into the star |
| B．makes Tau Ceti different from the sun because it extends farther |
| C．is interesting because it keeps other planets away from Tau Ceti |
| D．plays a role in helping decide whether the five planets are real |
