What is the meaning of the word 'phenomenon' in the second paragraph?

Correct Answer: C

Rationale: In the context of the second paragraph, 'phenomenon' refers to something significant and unusual, specifically describing the scientific phenomenon known as the Doppler Effect. This effect explains the change in frequency of sound waves when a source of sound and the observer are in relative motion. Choices A, B, and D are incorrect because they do not accurately reflect the meaning of 'phenomenon' in this context. 'Lifeless to the senses,' 'nonchalant,' and 'chemical in origin' do not align with the description of the Doppler Effect, which is a notable and uncommon scientific occurrence.

Correct Answer: A

Rationale: 'Elasticity' refers to the ability of the arterial walls to resist and be flexible, which affects blood pressure. In the provided extract, it is mentioned that an increase in blood pressure can occur if the arterial walls lose some of their elasticity with age or disease. This demonstrates that elasticity refers to the property of being able to resist and be flexible, supporting choice A as the correct answer. The other choices, B, C, and D, do not accurately reflect the concept of elasticity in the context of arterial walls and blood pressure.

Correct Answer: D

Rationale: In the context provided, 'popular' refers to magazines intended for the general public. The paragraph mentions that Infotrac indexes hundreds of popular magazines and newspapers, including medical journals such as the Journal of the American Medical Association and New England Journal of Medicine. These magazines target a wide audience, making choice D ('for the general public') the correct answer. Choices A, B, and C are incorrect as they do not align with the context of the paragraph.

Correct Answer: B

Rationale: Sound waves that are farther apart have a lower pitch. The Doppler Effect explains that as objects emitting sound move away, the sound waves become more spaced out, resulting in a lower frequency and a lower pitch. Choice A is incorrect because waves that are closer together have a higher frequency and a higher pitch. Choices C and D are not directly related to determining the pitch of sound waves.

Correct Answer: A

Rationale: The corrected statement should be: Changes in the ECG are not typically used for the diagnosis of abnormal cardiac rhythm. The passage mentions that the heart sends out electric currents in waves, and the 'wave of excitation' spreads through the heart wall accompanied by electric changes. It details the process of how the heart's electric impulses are recorded and how abnormalities can be detected. However, it does not state that ECG changes are specifically used for diagnosing abnormal cardiac rhythms. Choice A is the correct answer because it misrepresents the information provided in the passage. Choices B, C, and D are all supported by the passage and align with the details mentioned regarding the electrocardiogram and the wave of excitation in the heart.

Correct Answer: A

Rationale: Sound waves that are closer together have a higher pitch. This is explained by the Doppler Effect, where as a source of sound moves closer to an observer, the waves are compressed, resulting in a higher frequency and a higher pitch. Conversely, when the source moves away, the waves are stretched, leading to a lower frequency and a lower pitch. Therefore, choice A is correct. Choices B, C, and D are incorrect as they do not accurately describe the relationship between sound wave frequency and pitch.

Correct Answer: A

Rationale: In the context provided, 'composed' means to consist of. The paragraph explains that a drop of water is composed of an oxygen atom and two hydrogen atoms. Therefore, the correct answer is A. Choice B, 'To be uniquely discovered,' is incorrect as it does not relate to the composition of a drop of water. Choice C, 'To be set apart,' and Choice D, 'To be surprised,' are also incorrect as they do not convey the meaning of 'composed' as it is used in this paragraph.

Correct Answer: B

Rationale: In the context provided, 'emitting' means releasing, specifically referring to the electric currents being released in the body. The passage describes how electric currents are constantly being emitted in the body and can be detected on the body's surface, ultimately recorded by an electrocardiograph. This process is about the release of electric impulses, making 'releasing' the correct interpretation. Choice A, 'Repelling,' implies pushing away, which is not the intended meaning in this context. Choice C, 'Closing,' and Choice D, 'Charging,' do not align with the context of electric currents being emitted.

Correct Answer: A

Rationale: The correct answer is 'A: requiring expert knowledge.' In the context provided, 'technical' refers to articles that demand expert knowledge to understand. The passage mentions that articles published in medical journals can be technical, meaning they are complex and require specialized expertise to comprehend. Choice B, 'incomplete,' is incorrect as 'technical' does not imply incompleteness. Choices C and D, 'foreign' and 'plagiarized,' are also incorrect as they do not align with the context of the passage.