Correct Answer: C

Rationale: The correct summary of the passage is option C. The passage explains how the ECG systematically measures and records the 'wave of excitation' that occurs within the heart in three distinct steps, spreading from the SA node to the AV node. This summary effectively captures the main focus of the passage. Option A is incorrect because it only mentions the detection of electric currents in the body and recognizing abnormalities by medical staff, missing the key information about the 'wave of excitation' and its stages. Option B is incorrect as it focuses solely on the measurement and recording of unique electric currents on the body's surface, neglecting the specific process described in the passage. Option D is also incorrect as it provides a general description of how the ECG measures electric currents without emphasizing the specific stages of the 'wave of excitation' as detailed in the passage.

Correct Answer: B

Rationale: In the context of the given extract, 'evolved' means to gradually develop. The systems in the body have evolved over time, indicating a gradual development and adaptation. 'To spread,' 'to revolve,' and 'to shift' do not capture the idea of a gradual development as portrayed in the text, making them incorrect choices.

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.

Correct Answer: A

Rationale: In the context of the immune system, 'enlist' means to call into service. Immune cells recruit other cells to fight infection by producing chemicals that regulate their growth, behavior, and direct new recruits to trouble spots. This process is essential for the immune system's defense mechanism. The other choices are incorrect: 'write down' and 'put across' do not capture the action of mobilizing immune cells, and 'send away' is opposite in meaning to what is happening in the immune response.

Correct Answer: A

Rationale: The correct answer is A: 'foodborne illnesses.' The passage discusses how foodborne illnesses are contracted by consuming contaminated food or beverages, the symptoms they can cause, common sources of contamination like bacteria, viruses, and chemicals, and preventive measures. While the passage mentions dangers associated with uncooked food, bacteria, and proper food preparation, the primary focus is on foodborne illnesses caused by various contaminants. Choice B, 'the dangers of uncooked food,' is incorrect as it is a narrower focus compared to the broader topic of foodborne illnesses. Choice C, 'bacteria,' is incorrect as it is one of the contaminants discussed in relation to foodborne illnesses but not the central subject of the passage. Choice D, 'proper food preparation,' is incorrect as it is mentioned in the passage but not as the main subject; rather, it is discussed as a preventive measure to avoid foodborne illnesses.