Passage 3
　　In science, a theory is a reasonable explanation of observed events that are related. A the-ory often involves an imaginary model that helps scientists picture the way an observed event could be produced. A good example of this is found in the kinetic molecular theory, in which gases are pictured as being made up of many small particles that are in constant motion.?
　　A useful theory, in addition to explaining past observations, helps to predict events that have not as yet been observed. After a theory has been publicized, scientists design experi-merits to test the theory. If observations confirm the scientists’ predictions, the theory is sup-ported. If observations do not confirm the predictions, the scientists must search further. There may be a fault in the experiment, or the theory may have to be revised or rejected.
　　Science involves imagination and creative thinking as well as collecting information and performing experiments. Facts by themselves are not science. As the mathematician Jules Henri Poincare said: "Science is built with facts just as a house is built with bricks, but a collection of facts cannot be called science any more than a pile of bricks can be called a house." Most scientists start an investigation by finding out what other scientists have learned about a particular problem. After known facts have been gathered, the scientist comes to the part of the investigation that requires considerable imagination. Possible solutions to the problem are formulated. These possible solutions are called hypotheses.?
　　In a way, any hypothesis is a leap into the unknown. It extends the scientist’s thinking beyond the known facts. The scientist plans experiments, performs calculations, and makes ob-servations to test hypotheses. For without hypotheses, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories.
　　11. The word "this" in the 3rd sentence in paragraph 1 refers to ______.
　　A) a good example?
　　B) an imaginary model
　　C) the kinetic molecular theory?
　　D) an observed event
　　12. Bricks are mentioned in the 3rd paragraph to indicate how ____.
　　A) mathematicians approach science
　　B) building a house is like performing experiments
　　C) science is more than a collection of facts
　　D) scientific experiments have led to improved technology
　　13. In the last paragraph, the author refers to a hypothesis as "a leap into the unknown" in or-?der to show that hypotheses ______.
　　A) are sometimes ill-conceived?
　　B) can lead to dangerous results
　　C) go beyond available facts?
　　D) require effort to formulate
　　14. What is a major function of hypotheses as implied in the last paragraph7
　　A) Sifting through known facts.
　　B) Communicating a scientist’s thoughts to others.
　　C) Providing direction for scientific research.
　　D) Linking together different theories.
　　15. Which of the following statements is supported by the passage?
　　A) Theories are simply imaginary models of past events.
　　B) It is better to revise a hypothesis than to reject it.
　　C) A scientist’s most difficult task is testing hypotheses.
　　D) A good scientist needs to be creative.
　　Passage 3

　　文章大意：

　　這篇文章從定義、作用及產(chǎn)生過程幾方面闡述了科學(xué)理論?？茖W(xué)理論是對觀察到的相關(guān)事物的解釋。經(jīng)常包括一個(gè)想象的模式來幫助科學(xué)家想象事物的產(chǎn)生過程。而一個(gè)實(shí)用的理論，不僅可以解釋以往的觀察，還可以幫助預(yù)測等待觀察的事物。觀察又可以驗(yàn)證一個(gè)理論是否正確。科學(xué)除了包括收集信息和做實(shí)驗(yàn)，還需要?jiǎng)?chuàng)造性的思考，然后形成可能的問題解決方法，即假設(shè)。假設(shè)總是朝著未知領(lǐng)域前進(jìn)一步，它拓寬了科學(xué)家的視野，經(jīng)過驗(yàn)證后的假設(shè)就變成了理論。

　　答案解析：

　　[11]B第三句話中的代詞“this'’指代前一句提到的“an imaginary model"。因?yàn)檫@個(gè)例子就是要說明在動(dòng)力分子理論中，氣體被描繪成由許多不停運(yùn)動(dòng)的小分子所組成，即前句中“理論常包含一個(gè)想象模式來幫助科學(xué)家描繪事件的產(chǎn)生過程?！?/p>

　　[12]C第三段最后一句中“科學(xué)是由事實(shí)構(gòu)成的，就象房屋是由磚建成的。但是事實(shí)堆積起來并不能成為科學(xué)，這比用磚塊搭房子復(fù)雜得多”。因此說科學(xué)并不是簡單的堆砌事實(shí)。

　　[13]C最后一段第二句話，“假設(shè)”使科學(xué)家的思想可以超越已知事實(shí)。

　　[14]C最后一段第四句話，若沒有假設(shè)，更深入的調(diào)查就會(huì)缺少目標(biāo)和方向。所假設(shè)的一個(gè)主要作用就是給科研提供方向。

　　[15]D第二段第一句說明理論不僅可以解釋以往的觀察，還可以幫助預(yù)測還未觀察到的。

　　因此排除A。第二段最后兩句，如果觀察不能證實(shí)預(yù)測，那么說明實(shí)驗(yàn)有錯(cuò)或理論可能應(yīng)被修改或推翻，因此排除B。而C在文章中沒有涉及。根據(jù)第三段最后一句話，科學(xué)需要想象力和創(chuàng)造性思考，可以得出D為正確答案。