When they are studying to prepare for an exam, some students like to study with other people, while others like to study alone. Which do you prefer and why? 当他们在学习准备考试时,一些学生喜欢与他人一起学习,而另一些人则喜欢单独学习。你更喜欢哪个,为什么?
Talk about an Important Strength in the Schools in Your Country.Include reasons and examples to support your response. 说说你们国家学校教育的一项重要优势。用涵盖具体原因和例子的信息来支持你的回答。
Our country education has many strengths .The first is that it helps lay a solid foundation for our future study, because our country education is exam-oriented .To get high grades, we must work harder and learn as much as we can to be competitive in examinations. Second, the education of our country pay more attention to ……
1. What is the lecture mainly about?
(A) Ways to generate heat for nuclear fusion
(B) Differences between nuclear fission and nuclear fusion
(C) A controversial theory regarding how to generate nuclear fusion
(D) The possibility of establishing sustained nuclear fusion
2. According to the students, what are three advantages of nuclear fusion over nuclear fission
Click on 3 answers.
(A) Nuclear fusion can use a fuel that is more easily obtained.
(B) Nuclear fusion can be achieved at lower temperatures.
(C) Nuclear fusion produces more energy.
(D) Nuclear fusion does not produce hazardous by-products.
(E) Nuclear fusion does not require as many natural resources.
3. Why does the professor mention isotopes of hydrogen?
(A) To correct a student's comment about how fusion takes place in stars
(B) To help answer a student's question about temperature requirements for fusion reactors
(C) To explain what happens to hydrogen atoms during fusion reactions
(D) To justify the need for superconducting magnets in nuclear fusion reactors
4. According to the professor, how will the ITER reactor differ from earlier experimental fusion reactors?
Click on 2 answers.
(A) It will be transportable to different locations.
(B) It will sustain nuclear reactions through heat that it generates on its own.
(C) It will heat the fuel mixture to a higher temperature.
(D) It will confine the plasma in a more energy-efficient way.
5. What does the professor say about the international effort to develop ITER?
(A) The participation of many countries may cause ITER to be delayed even more.
(B) The research orientation of ITER has encouraged international collaboration.
(C) ITER will make use of equipment made in many different countries.
(D) The lack of international cooperation on earlier fusion projects has hurt ITER.
6. What does the professor imply when he says this:
(A) He prefers to work on projects with more immediate results.
(B) He believes that research in the physical sciences requires strict time lines.
(C) He thinks it will take less time to develop ITER than most researchers expect.
(D) He is more skeptical about the future of nuclear fusion than most researchers are.
类别：生物类 真题 150711CN-P2
Title：The Identification of the Genetic Material
The history of biology is filled with incidents in which research on one specific topic has contributed richly to another, apparently unrelated area. Such a case is the work of Frederick Griffith, an English physician whose attempts to prevent the disease pneumonia led to the identification of the material in cells that contains genetic informationthe information that determines an organism's characteristic structure. In the 1920s, Griffith was studying the bacterium Streptococcus pneumoniae, or pneumococcus, one of the organisms that cause pneumonia in humans. He was trying to develop a vaccine against this devastating illness. He was working with two strains of the bacteria pneumococcus. A bacterial strain is a population of cells descended from a single parent cell; strains differ in one or more inherited characteristics. Griffith's strains were designated S and R because, when grown in the laboratory, one produced shiny, smooth (S) colonies or groups of bacteria, and the other produced colonies that look rough (R).
When the S strain was injected into mice, the mice became diseased. When the R strain was injected, the mice did not become diseased. Bacteria of the S strain are virulent (able to cause disease) because they are surrounded by a protective jelly-like coating that prevents the mouse's immune defense mechanisms from destroying the bacteria before they canmultiply. The R strain lacks this coating. With the hope of developing a vaccine against pneumonia, Griffith injected some mice with heat-killed S pneumococci. These heat-killed bacteria did not produce infection. Griffith assumed the mice would produce antibodies to the bacteria that would allow them to fight the virulent form if they were exposed to it. However, when Griffith inoculated other mice with a mixture of living R bacteria and heat-killed S bacteria, to his astonishment, the mice became ill with pneumonia. When he examined blood from these mice, he found it full of living bacteriamany with characteristics of the virulent S strain. Griffith concluded that, in the presence of the dead S pneumococci, some of the living R pneumococci had been transformed into virulent S-strain organisms.
Did this transformation of the bacteria depend on something the mouse did to the bacteria No. It was shown that simply putting living R and heat-killed S bacteria together in a test tube yielded the same transformation. Next it was discovered that a cell-free extract of heat-killed S cells also transformed Rcells. (A cell-free extract contains all the contents of cells, but no intact cells.) This result demonstrated that some substance called at the time a chemical transforming principle from the extract of S pneumococci could cause a heritable change (a change that could be passed on to future generations) in the affected R cells. From these observations, some scientists concluded that this transforming material carried heritable information, and thus was the genetic material that scientists had been searching for.
The identification of the transforming material was a crucial step in the history of biology, accomplished over a period of several years by Oswald Avery and his colleagues at what is now Rockefeller University. They treated samples of the transforming extract in a variety of ways to destroy different types of substancesproteins, nucleic acids, carbohydrates, and lipidsand tested the treated samples to see if they had retained transforming activity. The answer was always the same: If the DNA (deoxyribonucleic acid) in the extract was destroyed, transforming activity was lost; everything else could be eliminated without removing the transforming ability of the extract. As a final step, Avery, with Colin MacLeod and Maclyn McCarty, isolated virtually pure DNA from a sample of pneumococcal transforming extract and showed that it caused bacterial transformation.
In retrospect, the work of Avery, MacLeod, and McCarty, published in 1944, was a milestone in establishing that DNA is the genetic material. However, at the time, it had little impact on scientists' view about the physical basis of inheritance. The genetic material had to encode all the information needed to specify an organism, and the chemical complexity and diversity of proteins were known to be impressive. So during the first half of the twentieth century, the hereditary material was generally assumed to be a protein. Nucleic acids, by contrast, were known to have only a few components and seemed too simple to carry such complex information.
Do you agree or disagree with the following statement: It is more important to have rules about the types of clothing that people wear at work and at school. 你同不同意下列陈述：制定关于人们在工作和在学校时的穿衣规则是非常重要的? 生活方式
2)建议写作思路：倾向于选择同意关于人们上班和上学时穿衣种类给出规则更重要。理由1：help bring equality to the school setting___ 理由2：workers were protective clothing for safety. 理由3 sense of being in a larger group" " With the development of technology, the design of clothing is various and we have abundant choices to make when it comes to what to wear at work and at school. However, from my perspective, it is more important to have rules about the types of clothing that people wear at work and at school.
To start with, requiring students to wear uniforms at school helps bring equality to the school setting. As the family background of the students is different from each other and what they wear at school usually tells others the economic situations of their family.……
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