Narrator:Listen to part of a lecture in an environmental science class.


  Professor:All right,folks,let’s continue our discussion of alternative energy sources and move on to what’s probably the most well-known alternative energy source,uh,solar energy.The Sun basically provides Earth with a virtually unlimited source of energy everyday but the problem has always been how do we tap this source of energy?Can anyone think of why it’s so difficult to make use of solar energy?


  Student A:Because it is hard to gather it?


  Professor:That’s exactly it!Solar energy is everywhere but it’s also quite diffused.And the thing is the dream of solar energy is not a new one,humanities have been trying to use the Sun’s light as a reliable source of energy for centuries.And,uh,around the beginning of the twentieth century,there were actually some primitive solar water heaters on the consumer market,but they didn’t sell very well.Any of you want to guess why?


  Student A:Well,there were other energy choices like oil and natural gas,right?


  Professor:Yeah!And for better or for worse,we chose to go down that path as a society.When you consider economic factors,it’s easy to see why.But then in the 1970s,there was an interest in solar energy again.Why do you think that happened?


  Student B:Because oil and natural gas were...err...became scarce?


  Professor:Well,not exactly.The amount of oil and natural gas in the Earth was still plentiful,but there were other reasons.Uh,it’s a political thing really and I’m not gonna get into that now.So what happened in the 1970s was:oil and natural gas became very expensive very quickly.And that spurred people to start looking into alternative forms of energy,solar energy probably being the most popular.


  But then in the 80s,this trend reversed itself when price of oil and natural gas went down.All right,let’s shift our focus now to some of the technologies that have been invented to overcome the problem of gathering diffused solar energy.


  The most basic solution is simply to carefully place windows in a building so that the Sun shines into the building and then it’s absorbed and converted into heat.Can anyone think of where this is most commonly used?


  Student A:Greenhouses.


  Professor:Yep,greenhouses where plants are kept warm and provided with sunlight because the walls of the building are made entirely of glass.But we do also have more complex systems that are used for space heating and they fall into two categories,passive and active heating systems.


  Passive systems take advantage of the location or design of a house.For example,solar energy is gathered through large glass panels facing the Sun.The heat is then stored in water-filled tanks or concrete.No mechanical devices are used in passive heating systems.They operate with little or no mechanical assistance.


  With active systems,on the other hand,you collect the solar energy at one location and then you use pumps and fans to move heat from the collectors through a plumbing system to a tank,where it can be used to heat a home or to just provide hot water.


  Student B:Excuse me,professor,but I’ve got to ask,“how can solar energy work at night or on cloudy days?”


  Professor:That’s,well,that is a really good question.As a matter of fact,science is still working on it,uh,trying to find ways in enhancing energy storage techniques,so that the coming of night or cloudy days really wouldn’t matter.That is the biggest drawback of solar energy,the problem of what do you do in cases where the sun’s light is weak or virtually non-present.So,the storage of solar energy,lots of solar energy is really an important aspect.


  Student A:Does that mean that solar energy can only be used on a small scale,like heating a home?


  Professor:Well,actually,there have been some attempts to build solar energy power plants.The world’s largest solar power plant is located in Kramer Junction,California.It can generate 194 megawatts of electric power,but that’s just a drop in the bucket.Right now the utility companies are interested in increasing the capacity of their Kramer Junction plant,but only time will tell if it will ever develop into a majorsource of power for that region,considering the economic and political factors involved.


  1.What is this lecture mainly about?

  A.An efficient solution to the problem of storing solar energy.

  B.Energy policies in the twentieth century.

  C.Reasons that solar energy is not more widely used.

  D.The superiority of solar energy to oil and natural gas.



  2.What are the two main problems solar power presents as an energy source?Click on two answers

  A.It is a potentially dangerous source.

  B.It is difficult to concentrate.

  C.It is scientifically unsound.

  D.It needs to be stored.


  题目解析:Because it is hard to gather it?(B选项)Solar energy is everywhere,but it’s also quite diffused.(D选项)综合原文,太阳能的最大两个问题就是存储和收集,分别在文中教授回答学生两次问题时出现。

  3.According to the professor,what led to the popularity of solar energy in the 1970's?

  A.New solar energy technologies.

  B.Advertising campaigns by solar energy companies.

  C.An increase in the price of oil and natural gas.

  D.The depletion of Earth’s reserves of oil and natural gas.


  题目解析:So what happened in the 1970s was oil and natural gas became very expensive very quickly,and that spurred people to start looking into alternative forms of energy,solar energy probably being the most popular.是因为油和天然气上涨的原因导致的。选C。

  4.What is the difference between passive and active heating systems?

  A.Passive systems are less reliable.

  B.Passive systems are difficult to install.

  C.Passive systems can be used at any location.

  D.Passive systems work without mechanical support.


  题目解析:No mechanical devices are used in passive heating systems.They operate with little or no mechanical assistance.由此可知,被动系统是不依赖任何机械设备的帮助的。因此D正确。文中未提及两系统的地点限制,因此C选项错误。

  5.What is the professor’s opinion about the future of Kramer Junction power plant?

  A.He is uncertain about the future of the Kramer Junction plant.

  B.He believes the Kramer Junction plant will become a major source of power.

  C.He is certain the Kramer Junction plant will not be able to increase its capacity.

  D.He thinks the Kramer Junction plant will have many competitors.


  题目解析:but only time will tell if it will ever develop into a major source of power for that region,considering the economic and political factors involved.教授在最后介绍了KJ,也就是一个太阳能发电厂,当提及它的前景时,教授说道“only time will tell.”说明他对其未来也并不确定,因此选A。剩下的选项均未提及。

  6.What does the professor mean when he says that?

  A.He thinks the student should know the answer.

  B.He thinks the student has raised an important issue.

  C.He wants the student to repeat his question.

  D.He will answer the question later in the lecture.


  题目解析:That’s...Well...that is a really good question.学生问道木有太阳的时候怎么用太阳能,然后教授口吃了。后面的时候也承认这是暂时无法解决的一个问题,也是一个重要的问题。根据重听部分语义理解,B正确。