共用题干
So Many"Earths"
The Milky Way（银河）contains billions of Earth-sized planets that could support life.That's the finding of a new study.It draws on data that came from NASA's top planet-hunting telescope.
A mechanical failure recently put that Kepler space telescope out of service.Kepler had played a big role in creating a census of planets orbiting some 170,000 stars.Its data have been helping astronomers predict how common planets are in our galaxy.The telescope focused on hunting planets that might have conditions similar to those on Earth.
The authors of a study,published in The Proceedings of the National Academy of Sciences,conclude that between 14 and 30 out of every 100 stars,with a mass and temperature similar to the Sun,may host a planet that could support life as we know it.Such a planet would have a diameter at least as large as Earth's,but no more than twice that big.The planet also would have to orbit in a star's habitable zone.That's where the surface temperature would allow any water to exist as a liquid.
The new estimate of how many planets might fit these conditions comes from studying more than 42,000 stars and identifying suitable worlds orbiting them.The scientists used those numbers to extrapolate（推算） to the rest of the stars that the telescope could not see.
The estimate is rough,the authors admit.If applied to the solar system,it would define as habitable a zone starting as close to the Sun as Venus and running to as far away as Mars.Neither planet is Earthlike (although either might have been in the distant past).Using tighter limits,the researchers estimate that between 4 and 8 out of every 100 sunlike stars could host an Earth-sized world.These are ones that would take 200 to 400 days to complete a yearly orbit.
Four out of every 100 sunlike stars doesn't sound like a big number.It would mean,however,that the Milky Way could host more than a billion Earth-sized planets with a chance for life.
The Kepler space telescope has been in service for 15 years.
A:Right
B:Wrong
C:Not mentioned

相关问题推荐

• 共用题干
  Have You Filled up the Form?
  Of all things in the world,I most dislike filling up forms;in fact,I have a______(51)horror of it. Applying for a living license,______(52)for an evening course,booking a holiday abroad一everything nowadays seem to involve______(53)information about one's personal life and habits that has little or nothing to do with the matter______(54)hand.When applying for a job,it may be______(55)some obscure interest to a______(56)employer to learn that I collect stamp or had measles as a child,but why should he conceivably want to know that my father was a tobacconist who died in 1988?
  The authorities who______(57)one to fill up forms,frequently demand answers to questions that one would hesitate to put______(58)one's intimate friends.The worst of it is that, when______(59)with such questions,my mind goes blank.Have I ever suffered from a serious illness?My mother always assured me I was"delicate".Do I suffer from any personal defects? Well,I wear contact lenses and my upper teeth are not my own,but perhaps the word"defects"______(60)to my character. Am I supposed to______(61)that I like gambling,and find it difficult to get up in the morning? Both of them are true.
  Of all,I think job applications are the worst,"education”一previous experience一post heldgive______(62）…Terrified by the awful warning about giving false______(63)which appear at the bottom of the form,I struggle to remember what exams I passed and how long I worked for what firms.______(64)hard I try,there always seems to be a year or two for which I cannot satisfactorily account and which I am certain,if left______(65),will give the impression that I was in prison or engaged in some occupation too dubious to mention.
  _________(55)
  A:by
  B:with
  C:about
  D:of

  查看答案
• 共用题干
  Music Used as a Healing Therapy
  1 .Music has long been used to treat patients suffering from different problems.In 400 BC,its healing properties were documented by the ancient Greeks. More recently,in both world wars in the last century, medical workers used music therapy（疗法）with people suf-fering from trauma（外伤）.Currently, it is used as a treatment for many diseases, such as cancer,and it has also been used with patients with long-term pain and learning disabilities.
  2 .There is growing evidence that music can caused physical changes to the body which can im-prove our health. In the Welcome Trust study,which took place over three years at the Chelsea and Westminster hospital in London,patients were asked to listen to musical perform-ances. As a result,it was found that stress levels were significantly reduced,recovery times were improved,and fewer drugs were needed.
  3. These very positive results are partly due to general well-being（良好的健康状况）.It is already accepted that when people feel happy and have a positive approach to life,they are more likely to feel better and recover from disease quickly. Music increases this feeling of joy and adds to the recovery process.
  4 .However,not all these benefits can be attributed to an increase in general well-being. Music has other effects which have not yet been understood. According to Professor Robert-son,a scientist and musician,some effects of music are mysterious and are,therefore,being investigated further. It has been suggested that the sounds and rhythms of music help stimu-late the brain and send electrical messages to the muscles.
  5 .Science,however,demands facts and hard evidence. Many in the medical profession have not yet recognized the healing benefits of music,since reports have been based mainly on various stories of evidence. These new studies could provide proof to doctors that music is a suitable treatment for many conditions. One day doctors may even “prescribe”（开处方） music,but that could be a long time in the future.
  Paragraph 4______
  A: Potential Dangers of Music Therapy
  B: Increase in General WellBeing
  C: History of Music Therapy
  D: Other Mysterious Effects of Music
  E: Positive Physical Changes Caused by Music
  F: Music and Your Body

  查看答案
• 共用题干
  U. S. Scientists Confirm Water on Mars
  NASA scientists said that Mars was covered once by vast lakes,flowing rivers and a Va-riety of other wet environments that had the potential to support life.
  Laboratory tests aboard NASA's Phoenix Mars Lander have identified water in a soil sample;the lander's robotic arm delivered the sample Wednesday to an instrument that iden-tifies vapors produced by the heating of samples.
  “We have water,”said William Boynton of the University of Arizona,lead scientist for ,the Thermal and Evolved-Gas Analyzer,or TEGA.“This is the first time Martian water has been touched and tasted.”
  The robotic arm is a critical part of the Phoenix Mars mission. It is needed to trench into the icy layers of northern polar Mars and deliver samples to instruments that will analyze what Mars is made of,what its water is like,and whether it is or has ever been a possible habitat for life.
  The soil sample came from a trench approximately 2 inches deep.When the robotic arm first reached that depth,it hit a hard layer of frozen soil.Two attempts to deliver samples of icy soil on days when fresh material was exposed were foiled when the samples became stuck inside the scoop.Most of the material in Wednesday's sample had been exposed to the air for two days,letting some of the water in the sample vaporize away and making the soil easier to handle.
  “Mars is giving us some surprises,”said Phoenix principal investigator Peter Smith of the University of Arizona.“We're excited because surprises are where discoveries come from. One surprise is how the soil is behaving. The ice-rich layers stick to the scoop when poised in the sun above the deck,different from what we expected,from all the Mars simulation tes-ting we've done so far.”
  Since landing on May 25,Phoenix has been studying soil with a chemistry lab,TEGA, a microscope,a conductivity probe and cameras.The science team is trying to determine whether the water ice ever thaws enough to be available for biology and if carbon-containing chemicals and other raw materials for life are present.
  The mission is examining the sky as well as the ground. A Canadian instrument is using a laser beam to study dust and clouds overhead.
  “It's a 30-watt light bulb giving us a laser show on Mars,”said Victoria Hipkin of the Canadian Space Agency.
  A full-circle,color panorama of Phoenix's surroundings also has been completed by the spacecraft.
  “The details and patterns we see in the ground show an ice-dominated terrain as far as the eye can see,”said Mark Lemmon of Texas A & M University,lead scientist for
  Phoenix's Surface Stereo Imager camera.“They help us plan measurements we're making within reach of the robotic arm and interpret those measurements on a wider scale.”
  Where are the scientists involved in the research from?
  A: They are from America.
  B: They are from Canada.
  C: They are from both America and Canada.
  D: They are from neither America nor Canada.

  查看答案
• The research team needs to confer with the director before it begins its final report.
  A:argue
  B:debate
  C:compute
  D:consult

  查看答案
• 共用题干
  As many as 20% of all children in the United States suffer from some form of the learning disorder called dyslexia.
  Experts on dyslexia say that the problem is not a disease.They say that persons with dyslexia use information in a different way.One of the world's great thinkers and scientists,Albert Einstein was dyslexic.Einstein said that he never thought in words the way that most people do.He said that he thought in pictures instead.The American inventor Thomas Edison was also dyslexic.Dyslexia first was recognized in Europe and the United States more than 80 years ago.Many years passed before doctors discovered that persons with the disorder were not mentally slow or disabled.The doctors found that the brains of persons with dyslexia are different.In most people,the left side of the brain一 the part that controls language is larger than the right side.In persons with dyslexia,the right side of the brain is bigger. Doctors are not sure what causes this difference.However,research has shown that dyslexia is more common in males than in females,and it is found more often in persons who are left handed.No one knows the cause of dyslexia,but some scientists believe that it may result from chemical changes in a baby's body long before it is born.They are trying to find ways to teach persons with dyslexia. Dyslexic persons think differently and need special kinds of teaching help.After they have solved their problems with language,they often show themselves to be especially intelligent or creative.
  Many great thinkers and scientists in the world are dyslexic.
  A:Right
  B: Wrong
  C:Not mentioned

  查看答案