MIT-SCIENCE-Lectures-homework3(1)

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MIT-SCIENCE-Lectures-f2000q

14.122Final ExamAnswer all questions.You have3hours in which to complete the exam.1.(60Minutes–40Points)Answer each of the following subquestions brieﬂy.Please show your calculations and provide rough explanations where you can’t give formal state-ments so I can give you partial credit.(a)Give a formal deﬁnition of what it means for a multistage game with observed actions to be continuous at inﬁnity?Why do we care whether games are continuous at inﬁnity?(b)Is the game below solvable by iterated strict dominance?Does it have a unique Nash equilibrium?(c)State Kakutani’s theorem.What correspondence is it applied to in the proof that anyﬁnite game has a Nash equilibrium?Where does the argument break down if you try to use Kakutani’s theorem in the same way to prove the existence of an equilibrium in the ”Name the Largest Number”game?(d)Is the following statement true or false:In genericﬁnite normal form games player 1’s equilibrium payoﬀis positive.(e)Find all of the subgames of the following extensive form game.(f)Given an example of a game in which you could argue that the subgame perfect equilibrium concept is too restrictive and rules out a reasonable outcome.Give an example of a game in which you could argue that the subgame perfect equilibrium concept is not restrictive enough and fails to rule out an unreasonable outcome.(Explain brieﬂy what you would argue about each example.)(g)Find all of the Nash equilibria of the following game.(h)Find the Nash equilibrium of the simultaneous move game where player 1chooses a 1∈ ,player 2chooses a 2∈ ,and the payoﬀs area 2+2 2u 1(a 1,a 2)=−(a 1−1)2 a 1−−2and a 1+2 2u 2(a 1,a 2)=−(a 2−3)2 a 2−−2.(i)Suppose that in class I presented the following slight variant on Spence’s job market signalling model.Nature ﬁrst chooses the ability θ∈{2,3}of player 1(with both choices being equally likely).Player 1observes θand chooses e ∈{0,1}.Player 2then observes e and chooses w .The players’utility functions are u 1(e,w ;θ)=w −ce/θ2and ∈ u 2(e,w ;θ)=−(w −θ)2For c =4.25this model has both a pooling equilibrium:(=2)=0∗θ1. (=0)=25∗e .2µ2(θ=2e =0)=0.5||s s (=3)=0∗θ1(=1)=2∗e 2µ2(θ=2e =1)=1s s and a separating equilibrium:(=2)=0∗θ1(=0)=2∗e 2µ2(θ=2e =0)=1||s s (=3)=1∗θ1(=1)=3∗e 2µ2(θ=2e =1)=0s s Suppose that after class two students come up to you in the hallway and ask you to settle an argument they are having about whether the equilibria fail the Cho-Kreps Intuitive Criterion.Assume that Irving arguesThe pooling equilibrium violates the intuitive criterion.The θ=3type couldmake a speech saying ‘I am choosing e =1.I know you are supposed to believethat anyone who gets an education is the low type,but this is crazy.The θ=2type would be worse oﬀswitching to e =1even if you did choose w =3.I,on the other hand,being the θ=3type will be better from having switched toe =1if you choose w =3.Hence you should believe that I am the high typeand give me a high wage.’Freddy arguesThe separating equilibrium violates the intuitive criterion.It is ineﬃcient.Be-fore he learns his type player 1could make a speech saying.‘This equilibrium iscation is of no value,yet with some probability I am going to have toincur substantial education costs.This is entirely due to your arbitrary beliefthat if I get no education I am the low type.If you instead believed that I wasthe low type with probability one-half in this case,then the return to educationwould be suﬃciently low so as to allow the ineﬃciency to be avoided.Moreover,this more reasonable belief would turn out to be correct as I would then choosee =0regardless of my type.’What would you tell them?22.(40Minutes–20Points)Consider the following multistage game.Player1ﬁrst has to choose how to divide $2between himself and player2(with only integer divisions being possible).Both players observe the division,and they then play the simultaneous move game with the dollar payoﬀs shown below.3Assume that each player is risk neutral and has utility equal to the sum of the number of dollars he or she receives in the divide the dollar game and the dollar payoﬀhe receives in the second stage game(a)Draw a tree diagram to represent the extensive form of this game.How many pure strategies does each player have in the normal form representation of this game?(b)Show that for any x the game has a Nash equilibrium in which player chooses to give both dollars to player2in the initial divide-the-two-dollars game.(c)For what values of x will the game have an unique subgame perfect equilibrium?(d)For what values of x is there a subgame perfect equilibrium in which player1gives both dollars to player2in the initial divide-the-two-dollars game.(e)Can the game have a subgame perfect equilibrium in which player1’s total payoﬀis less than2?3.(40Minutes–20Points)Harvard and MIT are both considering whether to admit a particular student to their economics Ph.D.programs.Assume that MIT has read the student’s application carefully and knows the quality q of the student.Assume that Harvard faculty members are too busy to read applications carefully.Instead they must base their decisions on their prior about the student’s ability.Harvard’s prior is that q may be1,2or3and that each of these values is equally likely.Assume that each school must make one of two decisions on the student:admit with ﬁnancial aid or reject(the student has no source of support and could not attend graduate school withoutﬁnancial aid).The schools make these decisions simultaneously.Assume that each school’s payoﬀin the game is0if they do not oﬀer the student admission,-1if the student is oﬀered admission and turns them down(this is costly both because the school loses prestige and because the slot could have been given to another student),and q−1.5if the student is oﬀered admission and decides to come.Assume that if the student is admitted to both schools she chooses to come to MIT with probability0.65and to go to Harvard with probability0.35.In the following questions treat this as a two player game between Harvard(player1) and MIT(player2).(a)What type spacesΘ1andΘ2would you use to represent this situation as a static game of incomplete information?How many elements are in each set?Write down the val-ues of the utility functions u i(a1,a2;θ1,θ2)for a couple values of i,a1,a2,θ1,θ2to illustrate how to compute them.How many pure Bayesian strategies does each player have?(b)What actions are strictly(conditionally)dominated for each possible type of each player?(c)Find the Bayesian Nash equilibrium of this game.(d)Would Harvard be any better oﬀif it could observe MIT’s admission decision before making its decision?44.(40Minutes–20Points)Consider the following model in which a worker’s choice of health play may signalhis health to his insurance company.Suppose natureﬁrst chooses the health of the workerchoosingθ∈{healthy,not healthy}.Assume that the probability that the worker is healthyis q.Player1observes whether he is healthy and then chooses a1∈{HMO,full insurance}. Player2,the competitive insurance market,observes a1and then chooses a price p for thechosen plan.Assume that the HMO plan will always pay half of the worker’s health care expenses,while the full insurance plan will pay all of the worker’s health care expenses.Assume thatthe worker’s expected health care expenses are$1000if the worker is healthy and$2000ifthe worker is not healthy.Assume that the worker is risk neutral and that his expectedutility from each health plan is equal to2000minus the sum of p and his unreimbursedhealth care expenditures,i.e.u1(HMO,p;healthy)=1500−pu1(full insurance,p;healthy)=2000−pu1(HMO,p;not healthy)=1000−pu1(full insurance,p;not healthy)=2000−pTo model a competitive insurance market assume that player2’s has a quadratic utilityfunction that makes it want to set p equal the expected payments that will be made undera plan,i.e.u2(HMO,p;healthy)=−(p−500)2u2(full insurance,p;healthy)=−(p−1000)2u2(HMO,p;not healthy)=−(p−1000)2u2(full insurance,p;not healthy)=−(p−2000)2(a)Does the model have a separating PBE where only the unhealthy workers buy fullinsurance?(b)For what values of q does this model have a pooling PBE where all types of player1buy full insurance?(c)Suppose that rather than there being just two types of player1there are a continuumof possible types.In particular,assume that player1observes his expected health careexpenditures for the year before making his health plan choice and that player2’s prior isthat these are uniformly distributed on[0,2000].What kinds of equilibria seem like theymight be possible in this model?Show that there is no PBE in which player1buys fullinsurance with positive probability.(d)What does this model suggest about the dangers of a free market in health insurance?What modiﬁcations to the model would be necessary if you wanted to think about theineﬃciency of health insurance more seriously?5。

我的科学家庭作业英文作文

我的科学家庭作业英文作文英文：As a student, I have had my fair share of science homework. It can be daunting at times, but with a littlebit of effort and curiosity, it can also be a lot of fun. In my experience, there are two main types of science homework: research-based and problem-solving.Research-based homework usually involves finding information on a particular topic and presenting it in a clear and concise manner. This type of homework requires a lot of reading and note-taking, but it can also be very interesting. For example, I once had to do research on the human brain and learned about the different parts and their functions. It was fascinating to learn how the brain controls everything we do, from breathing to thinking.Problem-solving homework, on the other hand, involves using scientific principles to solve a problem or answer aquestion. This type of homework can be challenging, but it can also be very rewarding. For example, I once had to calculate the velocity of a roller coaster at the bottom of a hill using the principles of physics. It was difficult, but when I finally got the answer, it felt like a huge accomplishment.中文：作为一名学生，我有很多科学作业需要完成。

麻省理工开放课程英语字幕物理3

let me write this down here--
and here we have vector B.
One way to look at this is the following.
You can say A minus B is A plus minus B and we know how to add vectors and we know what minus B is.
You have no information on their direction but you do know that the magnitude of one is four and the magnitude of the other is five.
When you add scalars, for instance, five and four then there is only one answer, that is nine.
Five plus four is nine.
Suppose you have two vectors.
You will see me at point S in 26.100 although I am still standing at the same location on the table.
The table has moved.
This is now the position of the table.
I take B and I bring it to the head of A.
So this is B, this is a vector and then the net result is A plus B.

MIT-SCIENCE-Lectures-thirdwrittenassn

21A230; SP 456JTHIRD WRITTEN ASSIGNMENTThis assignment is an exercise to get you to think comprehensively about policy-making and families. You are to construct a model of a much better, or perfect, family system for the U.S., to come about by the year 2007. What, in your opinion, would the most optimal family system look like?The concept of “family system” refers to the system made up of present-day families, including the opinions held by the majority of citizens about families as they ought to be. Of course none of us has full knowledge about every aspect of either actual families or what people think would be ideal families. Don’t worry about the incompleteness of your knowledge, just begin your discussion of present-day families and Americans’ notions about ideal families by saying something like “the following is my impression of what the present-day family system in the U.S. looks like, and what the majority of Americans believe families ought to look like.” International students: don’t worry that you know less than native-born Americans; if you use the class readings you’ll do fine.The bulk of your paper will be an assessment of what needs to be changed in families currently—a critique of the present-day family system. Because you’ll discuss the main faults, shortcomings, and defects of our current system (including what’s wrong with Americans’ notions of the ideal family), your critique will constitute the backdrop for your proposed model of a much better, if not perfect, family system.Your model of a better, or optimal family system should include descriptions of:1. The major structural changes required to bring about your much-improved orperfect family system.2. The important cultural changes required to ensure that a majority of people freelyaccept, value, and are willing to make sacrifices to maintain this utopian familysystem.3. A brief description of how these changes would be instituted—how they wouldcome about. In the schools? In the mass media? In the legislature? Through theefforts of elected officials like the president? In other institutions? If you includelegislation, remember that it can be state or municipal as well as federal.While you don’t have to cite sources when describing your much-improved/utopian family system (you may, though), you do need to cite sources during the part of your paper describing and critiquing the present-day family system.Don’t worry about the impossibility of bringing such changes to pass in 2 years. The deadline is set at 2007 so you won’t spend too much time predicting what the country will be like.2 Your model needs to be internally consistent and logical. The changes you make must be consistent with the information you have acquired in this class about families in the U.S. at present. That is, if you arrange for all mothers (or fathers) to be at home taking care of their children up to age 14, then you must discuss the implications of this change regarding family income, husband-wife interaction, etc.Discuss the larger context. Do not speak exclusively of individual nuclear families as if each one were an island in the ocean, unconnected to the larger society.It’s OK if your model seems unlikely to come about. However, your model must be possible. For example, you cannot build in Martian day-care providers or solve problems by having the federal government award each family $100,000 per child.Your model does not have to be of the “one-size-fits-all” type. However, if you include more than one model, you must describe each one comprehensively.You should provide some discussion of how your model accommodates families in different social classes, minimally the middle and working classes. Extra points if you include the upper classes and the extremely poor (sometimes called the underclass, or the “truly disadvantaged”). 7+ pp.Please cite at least six class readings in your exposition.Handed out: April 13Due in class: May 4。

MIT-SCIENCE-Lectures-sktn3

Sam Korb21M.735 Tech Note 3: StairsSqueaky StairsTechnical theater is in large part the art of building and creating to achieve exactly the right effect on the audience. Unwanted features detract significantly from the theatrical performance, and can be distracting or annoying to the audience. Stairs are a common theatrical element of scenery, but also one prone to malfunction in the form of squeaking.Stairs are composed of three elements: treads, risers, and stringers. The first two are more or less self explanatory: the treads are the horizontal pieces of wood on which one treads, and the risers are the vertical pieces of wood that rise from tread to tread. The stringers are what hold it all together – they are the pieces with zigzag patterns cut out that the risers and treads are attached to. From the business end of the stair, where one walks, the stringers aren’t visible in a normal staircase. For many staircases, theatrical ones in particular, it is possible to get access to the underside of the staircase, and this can be very helpful in addressing squeaking.Squeaking is caused by the wood of the stairs shrinking or warping over time, by the strains of use, or poor original construction. Seasonal contraction and expansion of the wood can also play a part in causing the structure to loosen up. Stairs constructed of glue in addition to metal fasteners (screws and nails) are less prone to squeaking. The squeaking sound comes from the rubbing of wood against wood. This occurs when the tread comes loose from stringer, or the tread rubs or knocks against the riser.There are methods of stair repair that can be applied from both the top and the bottom. The advantage of going at the stair from the bottom is that the fix doesn’t haveto be as aesthetically pleasing, and can indeed leave material below the step, like blocks or wedges. However, in some cases, the bottom of the stair is inaccessible; in that case repairing from the top is the only option baring ripping out an existing wall. It can also be easier to work from the top, as it doesn’t involve inserting screws upwards above your head.When repairing any stair, it usually helps to have a helper stand on the step to push it closer to the stringer or riser, so that the repair will involve fastening the two parts together, not trying to use the power of the fastener to pull the parts together.Options for stair repair from the top involve nailing the tread into the part it has come loose from, screwing the tread in, or inserting small wooden wedges in between the tread and riser, coated with glue. After the glue dries on the wedge, the exposed portion should be cut away with a knife. As referred to above, it is important to remember that above-the-stairs repairs should be finished with appearance in mind: countersink and putty over nail and screw heads, and make sure wedges are discreet. To this end, molding can occasionally be used on stairs where the wood is exposed to act as a block to fasten the tread to the riser.Options for below-the-stairs repair include basically everything that can be done above, as well as using metal brackets between the treads and stringers and gluing blocks from below and then nailing them into place. Whenever nailing a tread to a stringer, it is good to use two nails at opposing 45 degree angles (pre-drill to get the angle right). This way, they act as a clamp, and are much less likely to work themselves out. And for a quick fix, joints can also be lubricated with graphite powder, but this won’t solve the problem forever.Given this knowledge of the anatomy of stairs, and the solutions proposed, almost any squeaky stair should be manageable.On a final note, it is conceivable that a squeaky stair could be a design parameter for a piece of scenery, for example if a set was to be of an old or spooky house. Though none of the literature covered this particular issue, I feel that here too, the knowledge of the dynamics of squeak are very useful. Basically, one could try to implement the reverse of some of the fixes, for example, while still maintaining structural integrity, removing some of the fasteners, or perhaps adding more wood loosely fitted together, to encourage rubbing and squeaking. This would likely require some experimentation and tweaking, but is theoretically possible.Resources:/stories/Detailed/218.shtml/toh/print/0,17071,229734,00.html/bhg/printableStory.jhtml?storyid=/templatedata/bhg/how-to/data/14883.xml/bhg/printableStory.jhtml?storyid=/templatedata/bhg/step-by-step/data/hie_1158.xml/prel80/HDUS/EN_US/projects/pg_project.jsp?CNTTYPE=P ROD_META&CNTKEY=Know+How%2fproject&BV_SessionID=@@@@020437929 8.1077595044@@@@&BV_EngineID=ccchadckkifmmkhcgelceffdfgidgmn.0&MID=9 876&projectKey=Floors%2fStopping+Squeaks%2fStopping+Squeaks/Fixing_a_Squeaky_Stair_From_the_Underside/Fixing_Squeaky_Stairs_at_Stair_Level/questions/floorsqueaksq.html。

一年内自学MIT的33门课疯狂学习有方法

一年内自学MIT的33门课疯狂学习有方法能快速掌握复杂信息，对成就卓越事业至关重要。

ScottYoung 的学习过程不只适用于学生，同样有助于学习复杂技能的专业知识。

最近，在TED大会上，一位叫Scott Young的年轻人分享了他的一个惊人成就：他在一年之内，完成了MIT(麻省理工学院)计算机科学本科课程的全部33门课，并都通过了考试。

重要的是，他完全是靠自学完成的，观看在线教程的讲座，再参加实际的考试做自我评估。

MIT计算机科学的33门课，都是一些硬骨头，从线性代数到计算理论。

而且，MIT的课程不能用临时抱佛脚的方式完成，死记硬背行不通。

因为MIT的考试对解决问题的技巧要求很高，还会经常出一些没见过的题型。

其次，MIT的课程讲究循序渐进，就算你能侥幸通过一次考试，同系列课程的第七课可能就跟不上了。

Young能通过考试，主要是靠“加速理解的过程”。

Young自己是学商学出身，按照他的进度，读完一门课程只需要1.5个星期。

Young也把自己学习33门课的经验在自己的博客上做了分享，他并不准备因此就转行去做一个计算机工作者。

做这件事情的主要目的，是证明此事是可以做到的。

一年内如何自学MIT的33门课?尽管学得更快有很多好处，但大多数人并不愿意思考“如何学习”。

大概是因为我们不肯相信有这种好事，在我们看来，学习的速度只取决于好基因与天赋。

确实总有些人天赋异禀，但你的学习方法也很重要。

更深层次的知识加工，与时而反复的温故知新，在某些情况下会加快你的学习效率。

是的，研究表明，没有正确的方法，学习将永远停滞。

如何建立你的知识体系?大多数人经典的求学之路，就是听讲座，读书;如果还不懂，只好枯燥地做大量习题(题海)或重看笔记。

没有系统的方法，想更快地理解似乎是天方夜谭。

我们大概都经历过“啊哈!我懂了”的那种快乐，但对顿悟的心理机制全然不知。

而且理解本身，很难称得上是一种开关。

它像洋葱的层层表皮，从最肤浅的领会到深层次的理解，逐层巩固对科学革命的认知。

MIT-SCIENCE-Lectures-student3b

Student B:Though this is a minor point, while reading both the Thompson and Perry portions I was struck by what seemed like heavy influence from the Annales school, and Braudel's "Mediterranean" in particular. On themost basic level, the three part structures of both books conformloosely to a structure-conjencture-evenement format. The long-term influence of popular traditions form the "structure" in both cases,shorter term social phenomena are "conjenctures", and the relationship between social theory/theorists and Radical ideology/workers form the "evenements" sections in that they deal in detail with the interplay of theory and worker reality over time. Both authors lay stress onshort-term trends in data that might be viewed only as long-termstatistics in an economic study. Thomspon's explanation of thegradually increasing but oscillatory Methodist enrollment (390) andPerry's discussion of the causes of short term trends in Shanghai strike data (66) are reminiscent of Braudel's exposition of short-term andlocal trends in the gradually increasing economic activity of the Mediterranean. Both authors also emphasize the dynamic aspect of history, a point that Braudel stresses repeatedly. The Annales emphasis on the broader social causes of historical change is seen in everyaspect of "labor history", almost by definition. I'd like to brieflyaddress several examples of general trends in labor history and social history in general shown in both Thompson's and Perry's analyses, as such trends are much more significant when established across more than one historical case.Both Thompson and Perry give some primacy to the workers they study by arguing the contemporary point of view to be the most objective and emphasizing the importance of what people were thinking when a historical event happened for understanding that historical event.Perry places much emphasis on transcriptions of interviews conducted with Shanghai strikers 20-40 years after the fact, as in the comment of one former British Tobacco Company employee that during one huge Communist-led strike, she didn't know the strike had anything to do with Communists, but simply struck "because it seemed like the right thing to do" (150). This bolsters Perry's point that non-ideological concerns motivated many workers during strikes, and more generally that collective action spawned class consciousness at least as much as vice versa. In discussing the notion of "standard of living" as a measurable quantity, Thompson stresses that although "standard of living" does not necessarily correlate with economic indicators and will inevitably be biased if measured by some modern moral standard, it can be defined as the happiness of the people under study in the period being studied, as read through primary sources. The emphasis on the judgment of the worker as the most important and objective possible standard is an interesting aspect of these two authors' "labor history".Thompson and Perry focus on the role of labor, as opposed to the role of the much larger political and economic forces often studied. Given theall-encompassing way in which the latter kind of study can be presented, I was interested to see Thompson and Perry demonstrate a wide range of events and trends which only took place thanks to aspects of the labor force. For example, Perry lays constant emphasis on the central role of native-place identity in mobilizing Shanghai workers, given thatShanghai labor was deeply stratified by native-place in almost every imaginable way. In a discussion which I found fascinating, Thompsonnotes that the crucial problem in mobilizing English labor to work factories was instilling a sense of (mentally) internal discipline inthe population which would give men the ability to perform monotonous tasks for long shifts. Though this point must be contentious, Thompson claims this discipline was provided by the Methodist ideology which came to pervade what would be the working class, laying the basis for industrialization. The obvious question is how English labor was won over to a belief system which enslaved it, and not any other of the numerous Protestant ideologies present at the time. Thompson's answer is that Methodism was preached for workers by other workers who had accepted it. Without the religious and moral zeal that werehistorically determined parts of the working class English consciousness at the time, workers would not have preached and Methodism could not have spread. Both these examples are strong counterevidence for the view that the actions of workers were largely determined by external forces.。

MIT-SCIENCE-Lectures-assignment3 (2)

21H.421 Introduction to Environmental History (Spring 2004)Professor Harriet Ritvo; TA: Anya ZilbersteinASSIGNMENT 3: An Environmental History of Quabbin ReservoirPart I: Bibliographic essay (Assignment 2)Length: 5 pages plus annotated bibliography and research notesDue: In class, Tuesday, March 16Part II: Paper proposal, bibliography, and brief in-class statement of topic Length: 2-3 pages plus revised bibliographyDue: In class, Thursday, April 1Part III: Research paper and oral presentation to classLength: At least 10 pagesPresentation: About 10 minutesDue: In class, Thursday, May 13In this paper, you are going to try your hand at writing an environmental history of some aspect of the Quabbin Reservoir. In planning your paper you will have to make a number of decisions, starting with your choice of topic. You may write about any issue interesting to you that is similar to what we have been addressing in class. Some possibilities are human relationships with other species (plant or animal), vulnerability to diseases, exploitation of natural resources, or interaction with, and perceptions of, land and landscapes. The bibliographic essay you wrote for Assignment 2 is a good place to begin since you will already have familiarity with the sources, but you may choose another topic for the research paper. Be aware that if you choose to switch topics (as with any research project), you will first have to go through a process similar to what you did for the bibliographic essay, becoming acquainted with the relevant primary and secondary sources.Whatever topic you develop, it is better to be as focused as possible. We will schedule one-on-one meetings with each of you to help guide your transition from research to writing. But feel free to contact us to arrange a meeting at any point if you are stuck or just want to discuss research and writing strategies.In order to help you manage the process, this assignment is divided into three stages. In Part I, you made an annotated bibliography and wrote an essay describing those sources. In Part II, you will choose a topic to research in more detail, prepare a revised bibliography, and write a brief synopsis of your topic, research strategy, and a possible argument or set of questions that your research will address. Part II is due on Thursday, April 1. On that day, you should come to class prepared to give a five minute presentation about your project and to offer comments on other students’ presentations. Since you are all working with the same kinds of material, much of what your colleagues have to say should be interesting to you. Part III will consist of your completed paper, including footnotes and a full bibliography of your sources. The final paper is due on Thursday, May 13. In addition, each of you will give a ten minute presentation of your research, followed by a question period, on either May 11 or 13.CITATIONSAside from the bibliography, you must provide footnotes or endnotes to document the research for your paper. The first time an item appears in a note, you must provide the full and complete citation for it. Whenever the same item appears in later footnotes, you should use only the author’s last name and an abbreviated title, along with page references for the specific point you are either paraphrasing or quoting. The abbreviated title may be as short as one word or as long as a phrase. Sometimes you will want to cite an item in its entirely, without specifying particular pages or chapters. If you are quoting directly from a source in the body of your text, then your footnote must include the specific page number on which the quotation appears. Multiple sources in a single footnote (for example, when the point you are making integrates information from several sources), should be separated by a semicolon. The point is that the form of your footnote should allow your reader to identify uniquely the source(s) you are citing for the purpose you are using them in your text. Notice how the footnotes are indented and punctuated in the following examples. It is OK to use an alternative citation style that you have found in a reference guide, such as The Chicago Manual of Style, as long as you are consistent throughout your paper.Books:1 Richard White, The Organic Machine: The Remaking of the Columbia River (New York: Hill and Wang, 1995), chaps. 2, 3.2 White, The Organic Machine, 37.Chapters in edited volumes:3 Michal McMahon, “’Publick Service’ versus ‘Mans Properties’: Dock Creek and the Origins of Urban Technology in Eighteenth-Century Philadelphia,” in Early American Technology: Making and Doing Things From the Colonial Era to 1850 ed. Judith A. McGaw (Chapel Hill: University of North Carolina Press, 1994), 114-147.Journal articles:4 Susan Scott Parrish, “The Female Opossum and the Nature of the New World,” William and Mary Quarterly 3rd Ser. 54: 3 (Jul 1998): 475-514, quotation on 488. Manuscripts, images, and unpublished material:Images, including prints, maps, photographs and other types of visual evidence, must also be cited. If you have found an image in a book or other published source the guidelines are the same as above (though you should include the name of the artist if known). There is no universal rule for collections of unpublished or rare materials but your citations must give the following information: title and date of the item, series title (if appropriate), name of the collection, name of the depository, and page numbers (if appropriate). Here is an example of a letter archived in an archival collection of a local library.5 John Ebbets to John Jacob Astor, 11 January 1811, v. 33 f. 1, docs. 1788-1812, John Jacob Astor Collection, Baker Library, Harvard Business School.Online sourcesYou must give the complete URL and date you accessed information from online sources.。

homework3

Have you ever watered a garden and watched the water disappear(消失) into the soil? This fun experiment shows how plants take water from the ground to grow. Ask an adult to help you.You Will Need:• Medium-sized glass• Water• Red food coloring• Spoon• 1 celery stalk with leaves (一根带叶的芹菜)You Will Do:1. Fill the glass halfway with water.2. Stir(搅拌) in enough food coloring to make the water dark red.3. Ask Mom or Dad to cut 1 inch off the bottom of the celery stalk. Place the stalk in the water and let it stand overnight.What Will Happen?The leaves will turn red, as well as the tiny tubes running up through the stalk. Break the stalk in half, and you will see red dots in each piece.Why?As a plant grows, its roots act like straws(麦秆状吸管), sucking water up into the stem or stalk. Tiny tubes（管）inside the stalk carry water farther up into the leaves. (By coloring the water red, this is easier to see.) The red dots show a cross-section of the tiny tubes through which the water traveled.(190)51. What is this article mostly about?A. how water protects plantsB. how water can change colorsC. how celery stalks grow in waterD.how plants get water from the ground52. Which of these things is needed for Step 1 of the experiment?A. Water.B. Spoon.C. Celery stalk.D. Food coloring.53. In which part of the article can you find how the water moves through plants?A. “You Will Nee d”B.“You Will Do”C. “What Will Happen”D. “Why”F or one week in April, millions of people chose not to watch TV for “TV Turnoff Week”.TV Turnoff Week started in 1995 and is more popular every year. Many people discover that you can have a good time with the TV off. If that sounds crazy to you, just have a look at some numbers:―An American teenager spends 900 hours every year at school; the same teenager spends 1,023 hours every year watching TV. That’s 2 hours 49 minutes every day. ―An average（平均）British person (not just teenagers) watches 3 hours 35 minutes every day.―In the US, most TV has adverts. American children see 20,000 adverts every year. By age 65, an American has seen two million ads!But some research from Britain says that may not be a problem. The London Business School watched people carefully during TV adverts and they discovered that people don’t watch a lot of the ads. The researchers discovered that the most common activity during the adverts was talking to other people in the room. Many other people started reading or doing housework or changed channels during adverts. They only really watched them about 25 per cent of the time. 51．During TV Turnoff Week, many people don’t __________.A.watch TVB. change channelsC. watch advertsD. do their school work52．From the passage we can learn that __________.A. American children see more adverts on TV than their parentsB. British people spend more than 3 hours a day in front of their TVC. Researchers noticed that most people changed channels during adsD. An American teenager spends more time at school than watching TV 53．The writer’s purpose is __________.A. to advise us to spend less time on TVB. to tell us how to avoid watching advertsC. to show us how many adverts American TV hasD. to ask us to turn off TV during TV Turnoff WeekPassage3Picky, PickyScientists have no idea exactly why birds choose certain objects to build their nests. Butscientists know that the main reason birds build nests is to keep their babies safe, warm andhealthy.Baby birds grow faster and are healthier when they are warm. They also learn to fly and leavethe nests sooner than birds without warm homes.What A Yarn (纱)Oriole’s Nest Yarn is big on an oriole’s shopping list during nest building. Scientists are still trying to workout why so many birds choose white yarn over other colors for nest building.Scientists think that the white objects remind birds of cotton fluff (绒毛) they find in thewild.Do It NaturallyEven though birds can help us recycle some of our junk by using it to build nests, they alsoneed to use lots of natural things. Long grass, dried sticks, spider’s silk and mud are some of thenatural ingredients that are good for nests, too.You can make a collection box of things to leave for birds so they can help themselves. Hang asmall plastic box with holes on a tree branch. Fill the box freely with nest building goodies. Hangthe box on a tree and watch birds climb on board to pick through the junk to find their treasures.Warning: Don’t let the birds turn into a tasty treat. Keep your bird station away from placeswhere cats hang out.For The Birds!Stop! Don’t throw all that garbage out! Give some to the birds. Look and see how your oldjunk can help beautify and warm a bird’s new home.51. The baby birds with warm homes are able to _____.A. choose right objectsB. leave the nests soonerC. build good nestsD. learn to fly higher52. What can people make for birds to build nests?A. Holes on the tree.B. Food out of the rubbish.C. A warning board.D. A collection box of things.53. What can we learn from the passage?A. Birds build nests to store things.B. Birds regard white objects as cotton.C. Birds and humans can help each other.D. Birds and cats fight against each other.五、完形填空（共12分，每小题1分）On April 5,1971, the government of China asked the government of the United States this question. "Would the U.S. table tennis team like to 36 a week competing in pingpong games in China?" The answer was yes! For 20 years, Americans had not been allowed to 37 the land of China.The 15 members of the U. S. pingpong team did not know much about the country they were to visit. They had little 38 about the land or the population of China. Even so they found it different from what they 39 ! They had thought the people of China would be 40 and unfriendly. Instead, there were friendly Chinese everywhere waving and smiling.Never before had a sport become such a powerful instrument of 41 and friendship between two nations! The United States and China had been completely out of 42 with each other for many years. The visit of the American pingpong team to China brought about new efforts at communication 43 the two countries. The Chinese have 44 been the world table tennis champions(冠军), and they won most of the games. But who won the pingpong competition was not as 45 as the new friends that were 46 . "Winning doesn't 47 ," one of the Chinese players said, "but friendship does!"36. A. take B. pass C. use D. spend37. A. enter B. understand C. talk about D. get on38. A. question B. problem C. worry D. information39. A. imagined B. wanted C. had expected D. had seen40. A. foolish B. cold C. warm D. proud41. A. people B. sports C. war D. peace42. A. war B. touch C. trouble D. question43. A. of B. to C. between D. for44. A. never B. long C. always D. not45. A. many B. clear C. important D. special46. A. made B. known C. found D. met47. A. last B. exist C. develop D. mind书面表达英语校刊上刊登了学生会(The Student’s Union) 发出的倡议书“Write to your teacher”。

MIT-SCIENCE-Lectures-assignment_4(1)

6.837Introduction to Computer GraphicsAssignment4:Grid AccelerationDue Wednesday October15,2003at11:59pm This week,you will make your ray tracer faster using a spatial-acceleration data structure.You will implement grid acceleration,using fast ray marching. To convince yourself of the eﬃciency of your acceleration,you will analyze a set of statistics about your computation.In order to test your grid structure before using it for acceleration,you will implement the grid as a modeling primitive.Volumetric modeling can be implemented by aﬀecting a binary opaqueness value for each grid cell.This is the equivalent of the discrete pixel representation of2D images.Each volume element(or voxel)will be rendered as a solid cube.You can very easily rasterize simple primitives in a grid;for example,to rasterize a sphere,simply test the distance between the center of a voxel and the sphere center.After your grid modeling primitive is implemented and debugged,you will use it for acceleration.As a preprocess,you will insert all scene objects in the cells of the grid that they span.In order to test your object insertion code,you will render cells that contain one more more objects as opaque.Then,you will modify your ray tracer to use the grid for fast ray casting. You will use your ray marching code and intersect all the objects stored in each traversed cell.You must pay attention to intersections outside the cell and implement early rejection to stop marching when you have found an appropriate intersection.For this assignment,you may assume that no transformations are used.This way you may eﬀectively ignore the group hierarchy and insert all primitives by scanning the scene in a depth-ﬁrst manner.1Ray Tracing StatisticsUse the provided RayTracingStats class to compute various statistics including the number of pixels,the number of rays cast,the number of ray/primitive intersections,the number of cells in the grid,the number of grid cells traversed with the ray marching technique,and the total running time.Add the following timing and counter increment functions provided in the RayTracerStatistics class to your code:1• Call RayTracingStats::Initialize(int width,int height,int num_x,int num_y,int num_z,const Vec3f&min,const Vec3f&max)before beginning computation,• Call RayTracingStats::IncrementNumNonShadowRays()for each non-shadow ray(a call to RayTracer::TraceRay()),• Call RayTracingStats::IncrementNumShadowRays()for each shadow ray,• Call RayTracingStats::IncrementCellsTraversed()for each cell traversed(a call to MarchingInfo::nextCell()),• Call RayTracingStats::IncrementNumIntersections()for each ray/primitive intersection(not groups and transforms),and• At the end of your main loop,print the various statistics by callingRayTracingStats::PrintStatistics().From these numbers we can compute the average number of rays per pixel, intersections per ray,grid cells per ray,rays per second,etc.Verify that the statistics are reasonable for simple test scenes.To verify that the number of rays cast is correct,add a-no_shadows command line argument to your program. Test this part of the assignment with examples from last week.2GridDerive from Object3D a Grid class for an axis-aligned uniform grid.Initially a Grid will simply store whether each cell(voxel)is occupied so it can be rendered opaque or transparent.The constructor takes two Vec3f s describing the minimum and maximum coordinates of the grid,three integers describing the number of cells along the three axes,and a Material*.Grid::Grid(Vec3f min,Vec3f max,int nx,int ny,int nz,Material*m);An array of nx×ny×nz bool s stores whether each voxel is opaque or transparent.Implement the Grid::rasterizeSphere(Vec3f center,float radius) method that sets the opaqueness of each voxel by testing whether its center is inside the sphere described by center and radius.Test your sphere-rasterization routine on a small grid(e.g.,4x4)by printing the values of the array.23Fast Ray Marching with3DDDATo implement fast ray marching using3DDDA,you will need a place to store the information for the current ray and the current grid cell.Implement a MarchingInfo class that stores the current value of tmin;the grid indices i,j and k for the current grid cell;the next values of intersection along each axis (t next_x,t next_y,and t next_z);the marching increments along the three axes (dt x,dt y,dt z),and sign x,sign y,and sign z.To render the occupied grid cells for visualization you will also need to store the surface normal of the cell face which was crossed to enter the current grid.Write the appropriate accessors and modiﬁers.The intersection of a ray with a Grid will use two helpers to initialize the march and to move to the next cell.3.1InitializationFirst write:void Grid::initializeRayMarch(MarchingInfo&mi,const Ray&r,float tmin)const;This function sets the increments and the information relative to theﬁrst cell traversed by the ray.Make sure to treat all three intersection cases:when the origin is inside the grid,when it is outside and the ray hits the grid,and when it is outside and it misses the grid.Test your routine with a very simple grid,for example a4x4grid from(-2,-2,-2)to(2,2,2).Use simple rays for which you can manually test the result. For example,initialize the cell march for a ray with origin(0.5,0.5,0.5),or for a ray with origin(-2.5,0.5,0.5)and direction(1,0,0).Also test more general cases.3.2Marching stepNext,implement:void MarchingInfo::nextCell();This update routine choose the smallest of the next t values(t next_x,t next_y, and t next_z),and updates the corresponding cell index.Test your ray marching code using the same strategy as for initialization. For example,use a ray with origin(-3,-2,0.5)and directions such as(5,2, 0).Note that the problem reduces to a2D grid because the z component is0. Manually compute the marching sequence,and print the steps taken by your code.Try other origins and directions to make sure that your code works for all orientations(in particular,test both positive and negative components of the direction).33.3Putting it all togetherFinally,use these two helpers in your main grid-ray intersection routine.If the new cell is opaque,return the appropriate normal depending on which axis you advanced last.Test cases to visualize a simple sphere rasterization on your grid are provided.4Reducing the Number of IntersectionsIn order to use the grid as an acceleration structure,we must insert the scene primitives(but not groups and transforms)into the appropriate cells of the grid.First add two Vec3f s to your Object3D class to store the axis-aligned bounding box of each object.Add code to each subclass to compute these bounds(including Group and Transform).Verify that the computed scene bounding box is correct for various inputs.Next modify the Grid class to also store pointers to the objects whose bounding box overlaps the cell.You may use the provided Object3DVector class to store an arbitrary number of objects per cell.Finally,use the grid as a spatial acceleration for your ray caster.Implement two ray casting methods,RayCast(loops through all the objects in the scene as in previous assignments)and RayCastFast(uses the spatial acceleration data structure).Update your command line parsing so that the grid size may be speciﬁed at the command line: e.g.,-grid555.If no grid dimensions are provided,use the non-accelerated ray casting method.Pay attention to objects overlapping multiple cells—don’t incorrectly return intersections outside of the current cell.5What to Turn InFor each test scene,try diﬀerent grid sizes and report the choice yielding the fastest time,and discuss the eﬀect of this parameter on the running time.Provide a README.txtﬁle that discusses any problems you encountered,how long it took to complete the assignment,any extra credit work that you did and how we can test the new features.6Ideas for Extra CreditExperiment with other acceleration data structures(recursive/nested grid,octree,non-nested grid,bounding volume hierarchy,etc.);Supersampling;Other distribution ray tracing eﬀects;Flatten a scene graph which contains transformations by concatenating nested transformations;Compute a tight bounding box for each transformed triangle primitives by transforming the vertices;Test if the plane of the triangles intersects the grid cells;Volumetric rasterization4of other fun primitives;Use marking to prevent multiple intersections with a primitive that overlaps multiple cells;etc.7OtherObject3DVector(object3dvector.h)Stores an arbitrary number of Object3D pointers.You may use STL (Standard Template Library)instead if you prefer.Ray Tracing Statistics(raytracing_stats.h&raytracing_stats.C)A class of static member variables to store and compute various ray tracingstatistics.Parsing inputﬁles(scene_parser.h,and scene_parser.C) The SceneParser class has been extended to rasterize a sphere on a grid to help you debug your Grid class.New command line arguments-no_shadows(don’t cast any shadow rays)-grid555(dimensions for the spatial acceleration data structure)-visualize_grid(render the grid cells opaquely)-visualize_grid_count(OPTIONAL:render the grid cells opaquely,and use color to indicate cells which contain more objects)5。

外研版(三起)-英语-四年级下册--Moudle 3 Unit 1教材同步讲解

【新课堂】Moudle 3 Unit 1教材同步讲解模块内容导读新课导学大明有一个机器人，我们一起去看看机器人所具备的能力吧！机器人robot了不起，做housework没问题。

帮助孩子learn忙，homework可不能帮。

一周的假期就要到了，What will you do?早做打算，不匆忙。

语法索引Unit l（第一单元）1．情态动词can的用法 (44)2．he与his的用法 (45)3．she与her的用法…………………………………………………………………………(45)4．will的用法 (48)5．帮助某人做某事的表达 (49)6．won't的用法 (49)Unit 2（第二单元）7．辨析holiday与vacation (53)8．一般将来时的特殊疑问句 (53)9．go加动名词的用法 (54)10．辨析on，in与at (54)模块目标预览学前必备知识目标一、语音能够了解并掌握音标/k/，/t/，/w/，/ɔ:/，/ɔ/；能够区分音标/ɔ:/和/ɔ/的发音不同；注意字母组合wh的发音特点。

二、单词help（帮助，帮忙），our（我们的），have（有，拥有），next（下一个的），week（星期，周），holiday（假期），robot（机器人），will(将，将会)，everything(所有事情)，housework （家务活），learn（学习），homework（家庭作业），won't（将不会），Tuesday(星期二)，Wednesday（星期三），Thursday（星期四），Friday(星期五)三、短语ride a bike(骑车)，fly a kite（放风筝），make cakes（做蛋糕），next week(下周)，one day(将来(有一天)），on Monday（在周一），my new robot（我的新机器人）四、句型1．用情态动词描述能力的句型：“Sam/He... can+动词原形十其他”萨姆／他……能……2．描述将会做某事的句型：Robots will+动词原形十其他．机器人将会……I'll+动词原形十其他．我将……4．And they will help children learn.它们将会帮助孩子们学习。

MIT-SCIENCE-Lectures-midterm1

MIT-SCIENCE-Lectures-midterm114.04Midterm Exam1Prof.Sergei IzmalkovWed,Oct1 1.Let(p t,y t)for t=1,...,N be a set of observed choices that satisfy WAPM,let Y I and Y O be the inner and outer bounds to the true production set Y.Letπ+(p),π(p),andπ?(p)be pro?t functions associated with Y O,Y,and Y I correspondingly.(a)Show that for all p,π+(p)≥π(p)≥π?(p).(b)If for all p,π+(p)=π(p)=π?(p),what you can say about Y O,Y,and Y I?Provide formalarguments.(c)For(p1,y1)=([1,1],[?3,4]),and(p2,y2)=([2,1],[?1,2])construct Y I and Y O(graphically).What can you say about returns to scale in the technology these observations are coming from?Hint:think y=(?x,y).2.Given the production function f(x1,x2,x3)=x a1min{x2,x3}a,(a)Calculate pro?t maximizing supply and demand functions,and the pro?t function.What re-striction you have to impose on a?(b)Fix y.Calculate conditional demands and the cost function c(w1,w2,y).(c)Solve the problem py?c(w1,w2,y)→m ax y,do you obtain the same solution as in2a?Explainyour?ndings.3.Given the production function f(x1,x2)=x1+x b2,whereb>0,calculate the cost function c(1,1,y).How would costs respond to the changes in w1,w2,and y?How would factor demands respond? 4.Consider a?rm with conditional factor demand functions of the form(output has beenset equal to1for convenience):x1=1+w?131w a2,x2=1+dw b1w c2.What are the values of the parameters a,b,c,and d and why?5.The cost function is c(w1,w2,y)=w a1w b2y d.(a)What do we know about a and b?(b)What are the conditional factor demands?What is the production function?(c)What can you tell about returns to scale?6.Let c(w1,w2,ˉy)=ˉc(ˉy)be the isocost and y=f(x1,x2)=ˉy be the isoquant corresponding to a?xedoutpu t levelˉy=1.(a)What are the slopes of these lines?(b)Draw the isocost and isoquant for Cobb-Douglas technology y=x121x122corresponding toˉy=1.(c)Suppose c(w1,w2,1)=aw1+bw2.Draw the isocost and the corresponding isoquant(use theslopes to obtain the shape of the isoquant).(d)Repeat for c(w1,w2,1)=min{aw1,bw2}.(e)Draw conditional demand x1as a function of w1w2for7c and7d.Hint:If you have trouble in7c?7e,think what technology these costs came from.1。

八年级英语上册-人教版-Unit 3 说课稿(1)

八年级英语上册-人教版-Unit 3 说课稿（1）一. 教材分析人教版八年级英语上册Unit 3的主题是“My hero”，通过介绍英雄人物，让学生学会表达人物的特征、外貌、喜好等。

本单元的词汇和句子结构较为复杂，学生需要掌握一些形容词和副词来描述人物。

此外，本单元还涉及到了过去进行时态的用法。

二. 学情分析八年级的学生已经掌握了英语学习的基本语法和词汇，但部分学生在口语表达和写作方面还存在困难。

针对这一情况，教师在教学过程中要注重培养学生的口语表达能力和写作能力，同时激发学生的学习兴趣。

三. 说教学目标1.知识目标：学生能够掌握本课的生词、短语和句型，学会用英语描述人物的外貌、特征和喜好。

2.能力目标：学生能够运用所学知识进行口语交流和写作，提高英语实际运用能力。

3.情感目标：通过学习本单元，学生能够激发对英雄人物的敬仰之情，培养正确的价值观。

四. 说教学重难点1.重点：本课的生词、短语和句型。

2.难点：过去进行时态的用法以及如何用英语描述人物的外貌、特征和喜好。

五. 说教学方法与手段1.采用任务型教学法，让学生在完成任务的过程中运用所学知识。

2.运用多媒体教学手段，如图片、视频等，直观地展示人物形象，激发学生的学习兴趣。

3.小组讨论，鼓励学生积极参与，提高口语表达能力。

4.注重个体差异，给予学生个性化的指导和反馈。

六. 说教学过程1.导入：展示一些英雄人物的照片，让学生猜测并介绍这些人物。

2.新课呈现：通过图片和视频，展示本课的生词、短语和句型。

3.学生讨论：分组讨论，用英语描述自己喜欢的英雄人物。

4.口语练习：学生模拟介绍英雄人物，其他学生进行评价。

5.写作练习：让学生写一篇关于自己喜欢的英雄人物的短文。

6.课堂小结：总结本课所学内容，强调重点。

7.作业布置：让学生完成课后练习，巩固所学知识。

七. 说板书设计板书设计要简洁明了，突出本课的重点。

可以设计如下板书：Unit 3 My hero1.生词：hero, brave, kind, smart, doctor, nurse, artist, musician, athlete,champion2.短语：be famous for, have a good sense of humor, be strict with, workhard3.句型：How would you describe a hero?What does he/she look like?What does he/she like to do?八. 说教学评价1.口语评价：评价学生在课堂上的口语表达能力和参与程度。

七年级-人教版-英语-下册-[学习任务单]Unit-2-Section-B-(1a-1e)

Unit 2 What time do you go to school? (Period 3)Section B (1a-1e)学习目标学完这一课，你能够掌握：1．词汇half、past、quarter、homework、do (one’s) homework、run、clean、walk、take a walk；2．日常活动短语run、eat dinner、clean one’s room、do one’s homework、take a walk、go home等；3．能力：（1）掌握更复杂的时间表达方式（half、past、to、quarter、a.m./p.m.）；（2）what time 问答日常活动的句型。

课前学习任务【学习任务一】阅读教材第10 页1a活动，翻译下列时间。

1．早上六点半________________________________2．下午三点十五分________________________________3．晚上六点四十五分________________________________4．晚上九点四十五分________________________________【学习任务二】阅读教材第10页1c活动，翻译下列短语。

1．起床________________ 2．吃早饭________________3．去上学________________ 4．回家________________5．做我的家庭作业________________ 6．打扫我的房间________________7．吃晚饭________________ 8．散步________________9．上床睡觉________________课堂学习任务【学习任务一】根据图片所示用英语写出时间。

_______________ _______________ ______________________________ _______________ _______________【学习任务二】1．根据图片所示用英语（half、past、to、quarter）写出时间。

MIT-SCIENCE-Lectures-hw3_realworld

Sloan School of ManagementMassachusetts Institute of TechnologySpring 2004, H1Real-World ApplicationD UE D ATE:This team assignment is due by the beginning of class on March 9th.I NSTRUCTIONSChoose one of the four options below. Provide: Two- to three-page memo (plus any supporting tables, graphs, calculations, etc..) addressed to the relevant party in the game.1.Mixed Strategies (discussed in Lectures 3-4)Apply one of the games of Chapter 5 to a real-world application.Choose a game without an equilibrium in pure strategies and derive the mixedstrategy equilibrium. From this analysis, develop strategy advice for one of theplayers in the game or for a party interested in the outcome.2.Sequential / Repeated Games (discussed in Lectures 3-6)Apply one of the games of Chapter 3 or Chapter 8 to a real-world application.The game should have a temporal element. That is, it should either be a sequential game or a repeated game. Make sure to identify the length of the game as well as the players, strategies, and payoffs. From this analysis, develop strategy advice for one of the players in the game or for a party interested in the outcome.3.Strategic Moves (discussed in Lectures 5-8)Apply one of the games in Chapter 9 to a real-world application.Discuss how the parties might benefit from making / anticipating a strategic move. If relevant, address issues of observability, irreversibility, commitment, credibility, and how these may be achieved. From this analysis, develop strategy advice for one of the players in the game or for a party interested in the outcome.rmation (discussed in Lectures 8-10)1Describe an asymmetric information problem.Identify the source of the asymmetry and the information possessed by each party.How could signaling or screening help resolve this uncertainty? Is this a profitable strategy? Why or why not? From this analysis, develop strategy advice for one of the players in the game or for a party interested in the outcome.1 The assignment is due on Lecture 10. If you are working on option 4, you may turn in your assignment late (up until the last class on March 11th).。

Unit 3(第3课时 Section A grammar focus)(分层作业)解析版_1_1

Unit 3 My SchoolSection A(grammar focus) 第3课时(分层作业)【夯实基础】一、用be动词的正确形式填空1. There_____a photo on the wall.2. There______some plants near the desk.3. _________ there two apples on the desk?4. There__________a tall building and a beautiful garden in my school.5. _________ there a picture and a clock on the wall?6. How many kinds of animals_________there in the farm?7. There__________any ducks on the lake.【答案】1.is 2.are 3.Are 4.is 5.Is 6. are 7. are二、单项选择1．—Where is the post office?—It’s ________ Center Street. It’s across ________ the park.A．next to; on B．in; on C．on; from D．at; from2．I can’t see the words on the blackboard because there is a tall boy ________ me.A．next to B．across C．in front of D．behind 3．There are some cakes ________ this box. You can open it and eat the cakes.A．on B．in C．under D．Near 4．There ______ some old houses near my school last year.A．is B．are C．was D．Were 5．Look, ___________ many restaurants in front of the bank.A．has.B．haveC．there is D．there are6．There ________ a modern high-speed railway station in my hometown next year.A．be B．have C．will be D．will have【答案】1．C 2．C 3．B 4．D 5．D 6. C1.【详解】句意：——邮局在哪里呢？——它在中心大街上。

高考英语一轮复习话题发明家与发明(Unit 3 Inventors and

晨读背诵基础知识自测一、单词拓展(A)根据音标及词义写出英文单词｡1.distinguish [dɪˈstɪŋɡwɪʃ] vi. & vt.显示……的差别;使……有所不同;辨别2.merciful [ˈmɜːsɪfʊl] adj.宽大的;仁慈的;慈悲的→mercy [ˈmɜːsɪ] n.宽大;仁慈3.product [ˈprɒdʌkt] n.产品4.abrupt [əˈbrʌpt] adj.突然的;意外的→abruptly [ә'brʌptlɪ] adv.突然地,唐突地5.convenient [kənˈviːnɪənt] adj.便利的,方便的,就近的→convenience [kənˈviːnɪəns] n.方便,便利→conveniently [kənˈviːnɪəntlɪ]adv.便利地,方便地6.caution [ˈkɔ:ʃən] n.小心,谨慎→cautious [ˈkɔ:ʃəs] adj.小心的,谨慎的→cautiously[ˈkɔ:ʃəslɪ] adv.小心地,谨慎地7.passive [ˈpæsɪv] adj.被动的;消极的;被动语态的8.seize [si:z] vt.抓住;捉住;夺9.file [faɪl] n.文件;档案;文件夹 vt.提交;将……归档10.freezing [friːzɪŋ] adj.冰冻的;严寒的→freeze [friːz] v.冰冻11.innocent [ˈɪnəsənt] adj.清白的;无罪的;天真的→innocence [ˈɪnəsəns] n.天真,清白12.bear [beə(r)] vt.忍受;忍耐;负担13.tap [tæp] vt.轻打;轻拍;轻敲 n.轻轻地敲击(声);(水)龙头14.current [ˈkʌrənt] n.(水或气)流;电流 adj.现在的;当前的15.stable [ˈsteɪb(ə)l] adj.稳固的;稳定的;安定的16.associate [əˈsəʊʃɪeɪt] vt.联想;联系 n.同伴,伙伴17.practical [ˈpræktɪk(ə)l] adj.实际的;实践的;实用的petence [ˈkɒmpətəns] n.能力;胜任;本领(B)单词活用用所给词的正确形式填空｡1. I’m sorry, but I don’t know there is an abrupt ( abruptly)change of plan.2. As expected (expect), the sales manager gave in his notice at work today.3. We should try our best to put the enemy in a passive ( passive) position.4. As we all know, newspapers influence the current ( currently) of thought.5. I have heard two versions (version) of the accident.6．I t’s freezing (freeze) outside. You’d better put on more clothes. 7．Your invention is ingenious, but not very practical (practice). 8．I keep my reference books near my desk for convenience (convenient)．二、短语互译及运用(A)短语互译1.call up 给……打电话2.now and then 偶尔;有时3.set about 开始;着手4.dive into 迅速把手伸入;一心投入5.set out (to do) 开始(做)6.hang on 不挂断;稍等;紧紧握住7.out of order 次序颠倒;发生故障8.get through 设法联系上(尤指打通电话);(设法)做完;通过9.ring back 回复电话10.ring off 挂断电话(B)灵活运用选择以上恰当的词组填空｡1. The poor girl has gone through such a lot since her parents died.2. Do be careful with those fireworks; the slightest spark could set them off.3. These old photos called up childhood memories.4. I set out to knit(编织) a sweater but in the end it became a vest.5. He's not in; why don't you ring back after 6 o'clock?6. He takes my sister out to the theatre now and then.7. My clock is out of order and waked me up at 3 this morning.三、课文语法填空When I called up my mother in the countryside 1 the telephone she was upset. There were some snakes in the courtyard 2 came near the house now and then. I think here was a chance for me to distinguish 3 by inventing something to catch the snakes 4 I set about working on some approaches. Finally I came up with an easy 5 convenient way: I put a bowl with some ice-cubes in it 6 the snakes’ habitat to make them sleepy, then I used a small net 7 (collect) the passive snakes and the next day I merrily released them all back 8 the wild. I was satisfied with my invention that I decided to seize the opportunity to apply 9 a patent. So I sent my invention to the patent office to get recognition. And 10 after I have had the recognition can I say that I am truly an inventor.【答案】1. on 2. which/ that 3. myself 4. so 5. and 6. over 7. to collect 8. into 9. for 10. only重点词汇精讲精练1. distinguish vt.辨别；辨认；（常与from, between连用）区别；区分背诵 The man distinguishes himself by his wisdom这个人因智慧而扬名。