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Difficulty: MediumExplicit Main Idea

During expeditionary airfield construction, engineers frequently encounter unstable, water-saturated soils that cannot support heavy transport aircraft. To resolve this instability, crews lay synthetic geotextile fabrics directly over the subgrade before adding aggregate base layers. These permeable polymeric sheets prevent soft subsoil from mixing with the load-bearing crushed stone while simultaneously allowing subsurface water to drain away freely. By distributing localized wheel loads across a wider surface area, geotextile reinforcement serves as an indispensable method for stabilizing weak subgrades in military road and runway construction.

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

  1. A
    Permeable polymeric sheets prevent soft subsoil from mixing with load-bearing crushed stone while allowing subsurface water to drain.
  2. B
    Unstable, water-saturated subgrades present a primary engineering hazard for heavy transport aircraft during expeditionary deployments.
  3. Geotextile reinforcement serves as a vital method for stabilizing weak subgrades during military road and airfield construction.Answer
  4. D
    Synthetic polymeric fabrics have eliminated the need for conventional aggregate base layers across all military engineering projects.

Answer

The main idea of the passage is that geotextile reinforcement serves as a vital method for stabilizing weak subgrades during military road and airfield construction.
The passage describes the challenge of water-saturated subgrades and explains how geotextiles solve it, culminating in the explicit topic sentence stating that geotextile reinforcement is an indispensable method for stabilizing weak ground in military construction. The correct option directly paraphrases this central claim.

Step-by-Step Solution

1
Read the entire paragraph to understand the primary subject and determine what claim is made about it.
The passage discusses how engineers address unstable subgrade soils by installing geotextile fabrics underneath crushed aggregate layers.
Identifying the overarching topic helps separate the author's primary argument from supporting operational details.
2
Locate the explicit topic sentence that anchors the paragraph's core message.
The final sentence explicitly summarizes the central point: geotextile reinforcement serves as an indispensable method for stabilizing weak subgrades in military road and runway construction.
Explicit main ideas are directly articulated in the passage, often in the introductory or concluding sentence.
3
Evaluate the answer choices to identify the statement that captures this explicit thesis.
The statement expressing that geotextile reinforcement is a vital method for stabilizing weak subgrades accurately restates the passage's primary claim.
The correct main idea statement encompasses the full scope of the text without narrowing to minor details or exaggerating into unsupported claims.

Key Concept

Explicit Main Idea Identification
Estimated Time:1m 0s
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Explicit Main Idea

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