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

 Line     molecular theory, in which gases are pictured as being made up of many small particles

 (5)       that are in constant motion.  

                A useful theory, in addition to explaining past observation, 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

 (10)      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 will 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

 (15)      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

 (20)      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,

 

 

            1. Which of the following is the main subject of the passage?

              (A) The importance of models in scientific theories

              (B) The place of theory and hypothesis in scientific investigation

              (C) The sorts of facts that scientists find most interesting

              (D) The ways that scientists perform different types of experiments

 

 

            2. The word "related" in line 1 is closest in meaning to

              (A) connected

              (B) described

              (C) completed

              (D) identified

 

            3. The word "this" in line 3 refers to

              (A) a good example

              (B) an imaginary model

              (C) the kinetic molecular theory

              (D) an observed event

 

 

 

 

            4. According to the second paragraph, a useful theory is one that helps

             scientists to

              (A) find errors in past experiments

              (B) make predictions

              (C) observe events

              (D) publicize new findings

 

            5. The word "supported" in line 9 is closest in meaning to

              (A) finished                  (B) adjusted

              (C) investigated              (D) upheld

 

            6. Bricks are mentioned in lines 14-16 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

 

            7. In the fourth paragraph, the author implies that imagination is most

               important to scientists when they

              (A) evaluate previous work on a problem

              (B) formulate possible solutions to a problem

              (C) gather know facts

              (D) close an investigation

 

            8. In line 21, the author refers to a hypothesis as "a leap into the unknown

               in order 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

 

            9. In the last paragraph, what does the author imply is a major function of

               hypotheses ?

              (A) Sifting through known facts

              (B) Communicating a scientist's thoughts to others

              (C) Providing direction for scientific research

              (D) Linking together different theories

 

            10. 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