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Question

Difficulty: MediumExplicit Main Idea

Rotary-wing aircraft frequently operate in desert and coastal environments where airborne sand, dust, and rain strike the rapidly spinning blades. Over time, high-velocity particle impacts degrade composite laminates and induce micro-cracking along blade surfaces. To mitigate this wear, technicians apply sacrificial polyurethane erosion strips directly to the leading edges of the rotor blades. By absorbing kinetic impact and deflecting abrasive particles, these protective strips prevent severe structural deterioration of the underlying airfoil. Therefore, installing and maintaining leading-edge erosion strips is vital for protecting composite rotor blades from premature environmental degradation.

Which of the following best expresses the main idea of the passage?

  1. A
    All modern rotary-wing aircraft require extensive airframe overhaul to operate safely in desert and coastal environments.
  2. Leading-edge erosion strips play a vital role in shielding composite rotor blades from environmental wear.Answer
  3. C
    Technicians apply sacrificial polyurethane tape directly to the leading edge of helicopter rotor blades.
  4. D
    Composite laminates are less durable than standard metal alloys when exposed to high-velocity particle impacts.

Answer

The main idea of the passage is that leading-edge erosion strips play a vital role in shielding composite rotor blades from environmental wear.
The passage focuses on the function and necessity of leading-edge polyurethane erosion strips in safeguarding composite rotor blades from abrasive environmental damage. This core idea is explicitly stated in the concluding sentence of the paragraph.

Step-by-Step Solution

1
Analyze the passage structure to identify the central topic and locate explicit topic sentences.
The text details how particulate impacts damage rotor blades and identifies protective erosion strips as the solution.
Expository paragraphs often place the explicit main idea in an introductory or concluding synthesis sentence.
2
Compare the concluding sentence with the available answer choices.
The option emphasizing that erosion strips are vital for shielding composite rotor blades directly matches the final sentence.
The correct main idea summarizes the entire passage rather than highlighting an isolated supporting fact or an overbroad claim.

Key Concept

Identifying Explicit Main Idea in Technical Expository Prose
Estimated Time:1m 0s
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Explicit Main Idea

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