2. 外语
  3. Suppose we were in a spaceship in free fall, where objects are weightless, and wanted to know a small solid object’s mass. We co

Suppose we were in a spaceship in free fall, where objects are weightless, and wanted to know a small solid object’s mass. We co

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问题 Suppose we were in a spaceship in free fall, where objects are weightless, and wanted to know a small solid object’s mass. We could not simply balance that object against another of known weight, as we would on Earth. The unknown mass could be determined, however, by placing the object on a spring scale and swinging the scale in a circle at the end of a string. The scale would measure the tension in the string, which would depend on both the speed of revolution and the mass of the object. The tension would be greater, the greater the mass or the greater the speed of revolution. From the measured tension and speed of whirling, we could determine the object’s mass.
Astronomers use an analogous procedure to "weigh" double-star systems. The speed with which the two stars in a double-star system circle one another depends on the gravitational force between them, which holds the system together. This attractive force, analogous to the tension in the string, is proportional to the stars’ combined mass, according to Newton’s law of gravitation. By observing the time required for the stars to circle each other (the period) and measuring the distance between them, we can deduce the restraining force, and hence the masses.
Which of the following best describes the relationship between the first and the second paragraph of the passage?
选项 A、The first paragraph provides an illustration useful for understanding a procedure described in the second paragraph.
B、The first paragraph describes a hypothetical situation whose plausibility is tested in the second paragraph.
C、The first paragraph evaluates the usefulness of a procedure whose application is described further in the second paragraph.
D、The second paragraph provides evidence to support a claim made in the first paragraph.
E、The second paragraph analyzes the practical implications of a methodology proposed in the first paragraph.
答案A
解析 Evaluation
This question requires understanding that the second paragraph describes a somewhat difficult-to-understand procedure that the first paragraph illustrates in smaller, and simpler, terms.
A Correct. The first paragraph illustrates, hypothetically, a simple procedure for determining mass, and this illustration provides the grounds on which the passage explains the procedure of the second paragraph.
B The first paragraph describes a situation in hypothetical terms, but the second paragraph does not test that situation’s plausibility. Instead, the second paragraph draws an analogy between the initial situation and another procedure.
C The first paragraph does not evaluate the usefulness of the procedure for determining a small solid object’s mass while in a spaceship in freefall; it simply describes how that procedure would work.
D The second paragraph provides no evidence; it describes a procedure analogous to what is described in the first paragraph.
E The second paragraph does not discuss the practical implications of the first paragraph’s methodology but rather a procedure that is analogous to the hypothetical situation of the first paragraph.
The correct answer is A.
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