LearnVerbal AbilityReading Comprehension
15.02 · Reading Comprehension
Main Idea & Summary
Elite lesson9 rules10 questions
On the syllabus of
Video
Rules
At a glance 9 rules
- 1One-line summary firstBefore the options, say the passage in one line: its subject plus the author's point about it.
- 2Point after the turnWhen a passage turns on 'but', 'yet' or 'in fact', the main idea sits after the turn. The view before it is the usual trap.
- 3Examples are supportStudies, numbers, names and stories back the point. An option built on one of them is a detail, not the main idea.
- 4Cover the whole passageThe main idea fits every part of the passage. An option that fits one paragraph, one example or the last line alone is too narrow.
- 5Not too broadAn option that could head a whole book on the subject is too broad. Keep the passage's own subject and limits.
- 6Keep both halvesIf the passage weighs a gain against a cost, or gives two causes, the answer keeps both. An option with one half is half right.
- 7Match the author's strengthThe answer is as sure or as hedged as the author: 'can help' is not 'always solves'. Rejecting one extreme is not backing the other.
- 8Purpose: match the verbFor 'primary purpose', decide whether the author explains, argues, criticises or compares, then cut options whose first verb is wrong.
- 9Titles: subject plus angleA title carries the passage's subject and its angle. A catchy but vague title, or one detail dressed up as a title, fails.
Test yourself
Tap an option to answer. The first tap counts.
- Q1Easy
Mangroves are often treated as wasteland, swampy strips of coast to be cleared for ports, fish ponds or housing. Yet these salt-loving forests do a surprising amount of work. Their tangled roots slow incoming waves and storm surges, so villages behind a healthy mangrove belt tend to suffer less damage in cyclones. The same roots trap silt that would otherwise wash away, holding the shoreline in place. Young fish and crabs shelter among them, which keeps nearby fisheries stocked. A coast that clears its mangroves to gain a little land may end up paying for that land many times over.
Which of the following best states the central idea of the passage?
Correct answerMangroves protect coasts and livelihoods, so they are far from wasteland.
Why
Say the passage in one line first: mangroves look useless but do valuable work.
Every sentence after 'Yet' lists a job: slowing storm surges, holding the shoreline, sheltering young fish.
The silt line is one example, 'no land should ever be cleared' goes far beyond a passage about mangroves, and the open sea is never compared.
So the central idea is that mangroves protect coasts and livelihoods, so they are far from wasteland.
- Q2Easy
Read the passage and answer the question that follows.
No ant in a colony has a map of where the food lies or which route to it is shortest. Yet within an hour of a crumb being found, a colony often settles on an efficient path. The trick lies in a chemical trail. An ant returning with food lays down a scent that others tend to follow, and every ant that follows it adds scent of its own. Ants on a shorter route complete more round trips in the same time, so that route gathers scent faster, while the scent on longer routes fades because it evaporates before it is renewed. Over time the shorter path wins, not because any ant compared the routes but because the arithmetic of reinforcement and decay compared them for the colony. Computer scientists have borrowed this idea to plan delivery routes and to direct data through networks, letting many simple agents find good solutions that none of them could work out alone.
Which of the following best expresses the main idea of the passage?
Correct answerAn ant colony can find efficient routes through simple, repeated behaviour, without any single ant understanding the problem.
Why
Main idea must fit the passage from its first line to its last.
It opens with no ant holding 'a map', shows scent piling up on short routes and fading on long ones, and insists that no ant compared the routes; the colony gets there through repeated simple steps.
Each ant comparing routes reverses that, the evaporating trail is how the method works rather than a flaw, and the closing line is about planning routes, not building vehicles.
The main idea: an ant colony can find efficient routes through simple, repeated behaviour, without any single ant understanding the problem.
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