单选题 In science, a theory is a reasonable explanation of observed events that are related. A theory 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 experiments to test the theory. If observations confirm the scientists' predictions, the theory is supported. 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 observations to test hypotheses. For without hypotheses, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories.

单选题 The word "this" in the 3rd sentence in paragraph 1 refers to______.

【正确答案】 B

【答案解析】解析：本题是指代题。第三句话中的代词this指代前一句提到的an imaginary model。引用这个例子的目的在于在动力分子理论中，气体被描绘成由许多不停运动的小分子所组成，即前句中“A theory often involves an imaginary model that helps scientists picture the wayan observed event could be produced”(理论常包含一个虚构的模式来帮助科学家描述事物的出现过程。)

单选题 Bricks are mentioned in the 3rd paragraph to indicate how______.

【正确答案】 C

【答案解析】解析：本题是细节题。根据关键词bricks在原文找到其定位原句，即第三段的“Science is built with facts just as a house is built with bricks…”(科学是由事实构成的，就像房屋是由砖建成的。但是事实堆积起来并不能成为科学，这比用砖块搭房子复杂得多。)因此说科学并不是简单的堆砌事实。所以可判断C正确。

单选题 In the last paragraph, the author refers to a hypothesis as "a leap into the unknown" in order to show that hypotheses______.

【正确答案】 C

【答案解析】解析：本题是细节题。从题干中的关键词“a leap into the unknown”找到其定位原句“any hypothesis is a leap into the unknown”，接下来是对这一论点的深入陈述，即“It extendsthe scientist’s thinking beyond the known facts”(“假设”使科学家的思想可以超越已知事实)。由此可判断C正确。

单选题 What is a major function of hypotheses as implied in the last paragraph?

单选题 Which of the following statements is supported by the passage?

【正确答案】 D

【答案解析】解析：本题是细节题。第二段的第一句说明理论不仅可以解释以往的观察，还可以帮助预测还未观察到的。因此排除A。第二段的最后两句提到，如果观察不能证实预测，那么说明实验有错或理论可能应被修改或推翻，因此排除B。而C在文章中没有涉及。从第三段的第一句话可知，科学需要想象力和创造性思考，可以得出D为正确答案。