Why does the author mention 'impact craters' in line 16?

Correct Answer: C

Rationale: The mention of impact craters in the text is to highlight the consequence of the Moon lacking an atmosphere. The absence of an atmosphere on the Moon leaves it vulnerable to meteorite impacts, resulting in the multitude of impact craters on its surface. Choice A is incorrect because the mention of impact craters is not related to atmospheric weathering but rather to the lack of an atmosphere. Choice B is incorrect as it misinterprets the reason for the absence of plant life on the Moon. Choice D is incorrect as the text explicitly states that the Moon lacks tectonic or volcanic activity, which is not the focus of the mention of impact craters.

Correct Answer: D

Rationale: Strauss set up a net to ensure the safety of the workers in case of falls during the construction of the Golden Gate Bridge. Safety nets were essential to protect the workers from potential accidents or falls while working on the bridge. Choice A ('For suspension') is incorrect as safety nets were not used for suspension purposes but rather for worker safety. Choice B ('For balance') is incorrect as the balance of the bridge was maintained by other construction elements, not safety nets. Choice C ('For aesthetics') is incorrect as safety nets are not related to the visual appearance of the bridge but rather to the protection of the workers.

Correct Answer: D

Rationale: The correct analogy for the role of corrective lenses in helping aging eyes can be compared to an athlete stretching before a game. Just as stretching prepares an athlete's body to perform optimally and avoid injury during a game, corrective lenses help aging eyes adjust and focus properly due to the hardening and loss of elasticity in the eye lens. Choices A, B, and C do not align with the concept of preparing or adjusting to address a specific issue, unlike the use of corrective lenses for aging eyes.

Correct Answer: B

Rationale: Macmillan added iron rims to his bicycle tires to enhance their durability and make them last longer. This innovation aimed to prevent the tires from getting worn down quickly. Adding weight to the bicycle (Choice A) was not the purpose of adding iron rims. While adding iron rims could potentially reduce the bumpiness of the ride (Choice C) by providing more stability, the main objective was to improve tire longevity. Similarly, reducing the level of fatigue during the ride (Choice D) was not the primary reason for adding iron rims.

Correct Answer: D

Rationale: In the context provided, 'defective' means faulty, referring to the gene that causes cystic fibrosis (CF). The passage explains that CF is caused by a defective gene, resulting in the production of abnormally thick and sticky fluid. The word 'defective' suggests that the gene is not functioning correctly, leading to the symptoms associated with the disease. Therefore, 'faulty' is the correct choice. The other options, 'unusual,' 'remarkable,' and 'postponed,' do not accurately capture the meaning of 'defective' in this context and are therefore incorrect.

Correct Answer: D

Rationale: The correct answer is D because the passage specifically states that at the nanoscale, unique properties of materials emerge, which is a key benefit of nanotechnology. Choice A talks about what scientists can do but does not directly describe the benefits mentioned in the passage. Choice B is the definition of nanotechnology and not a specific benefit. Choice C mentions the use of different colors in medical tests, which is a specific application rather than a general benefit of nanotechnology.

Correct Answer: C

Rationale: The main idea of the passage is that innovations and improvements in bicycle design have made bicycles one of the most popular means of recreation and transportation worldwide. The passage outlines the evolution of bicycles from their early designs to the modern versions, emphasizing how these changes have contributed to their popularity. Choice A is incorrect because it focuses only on the current status of bicycles, while the main idea encompasses the evolution and improvements in design. Choice B is incorrect as it mentions the invention of the first modern bicycle but does not address the overall impact of innovations on bicycle popularity. Choice D is incorrect as it simply states a fact without capturing the essence of the passage, which is about the impact of design improvements.

Correct Answer: B

Rationale: The correct answer is B. Matter at the nanoscale exhibits unique and special characteristics that distinguish it from matter at larger scales. This can include properties like increased surface area, different melting points, altered conductivity, and enhanced reactivity. Choice A is incorrect as metals at the nanoscale can be more rigid compared to their larger scale counterparts. Choice C is incorrect because matter at the nanoscale has properties that are distinct from both atomic and larger scales. Choice D is incorrect as there are significant differences in how matter behaves and interacts at the nanoscale compared to larger scales.

Correct Answer: C

Rationale: The mention of impact craters in the text is to highlight the consequence of the Moon lacking an atmosphere. The absence of an atmosphere on the Moon leaves it vulnerable to meteorite impacts, resulting in the multitude of impact craters on its surface. Choice A is incorrect because the mention of impact craters is not related to atmospheric weathering but rather to the lack of an atmosphere. Choice B is incorrect as it misinterprets the reason for the absence of plant life on the Moon. Choice D is incorrect as the text explicitly states that the Moon lacks tectonic or volcanic activity, which is not the focus of the mention of impact craters.