Lesson 11 of 46 · Reading Comprehension
Detail and inference questions
Answer detail questions by going back to the text, and inference questions by taking the smallest step the passage forces, never a step it only allows.
About 20 minutes
In this lesson
- Locate the sentence a detail question depends on and match a paraphrase of it.
- Tell what a passage requires from what it merely leaves open.
- Reject inference choices that are too strong, out of scope or reversed.
The idea
Two kinds of question about the text
Detail questions ask what the passage says: "According to the passage…", "The passage states that…", "The author mentions X in order to…". The answer is in a particular sentence, usually in different words.
Inference questions ask what follows from what the passage says: "It can be inferred that…", "The passage suggests…", "The passage most strongly supports which statement…". The answer is not written in the passage, but the passage leaves no reasonable doubt about it.
The two need the same discipline: the answer must be supported by the text, not by what you know or what sounds reasonable.
Detail questions: go back every time
The words of a detail question point to a place in the passage. Go there, and reread the sentence that answers the question along with the sentences on either side, since the reason or qualification you need is often next door. Then put the answer in your own words before you read the choices.
The right choice is usually a paraphrase. A choice that repeats the passage's exact words is not necessarily right: wrong choices often borrow a phrase and attach it to the wrong claim. Read for meaning, not for matching words.
Inference: the smallest step
An inference on the GRE is not a guess about what the author might think. It is a statement that must be true, or is very strongly supported, given what the passage says. The right choice is usually modest: it takes one short step from the text, such as combining two sentences, or noticing what a contrast implies about the other side.
Ask of each choice:
- Can I point to the sentences that support it? If you cannot, it is out.
- Does the passage force it, or only allow it? "Some species did return" allows that most did, but does not force it. A choice that depends on "most" is out.
- Is it as strong as the text, and no stronger? Words like always, only, never, all and must need the same strength in the passage.
How wrong inference choices are built
| Kind | What it does | Example against "ants rarely carry seeds more than a few metres" |
|---|---|---|
| Too strong | turns "often" into "always", "some" into "most" | "Ants never carry seeds more than a few metres." |
| Out of scope | brings in something the passage does not discuss | "Seeds carried by birds germinate more often." |
| Reversed | swaps cause and effect, or the two sides of a comparison | "The attachment exists because ants carry seeds short distances." |
| True in the world, not in the passage | relies on outside knowledge | anything you know about ants that the passage does not say |
| Half right | one clause is supported, the other is not | a choice that is right about rodents and wrong about soil |
A half-right choice is wrong. Read every clause of a choice before you accept it.
Contrasts imply their other side
Many inferences come from contrasts. If the passage says a benefit "does not depend on how far the seed travels", you can infer that the benefit would remain even if ants carried seeds a very short distance. If it says a solution works "where a road was congested because of a single bottleneck", you can infer that the passage does not expect the same result where there is no single bottleneck. Asking "what does this contrast tell me about the other case?" is one of the most reliable ways to find the supported choice.
"The author mentions X in order to…"
This is a detail question about function. Find X, then ask what claim X supports or illustrates. The answer names that claim's role, not a fact about X itself. For example, the distances reached by wind-blown seeds are mentioned to show that the distance ants manage is trivial, not to teach anything about wind.
Worked examples
Example 1: A detail question
Many plant species produce seeds with a small fatty attachment that ants find attractive. An ant carries the seed back to its nest, the colony eats the attachment, and the seed itself, undamaged, is discarded in the nest's refuse chambers or just outside. Biologists first assumed that the plant's gain was distance: the seed ends up away from its parent. But ants rarely carry seeds more than a few metres, a trivial distance compared with that reached by seeds blown by the wind or eaten by birds. Two other benefits are now thought more important. Seeds buried in a nest are hidden from the rodents that eat seeds left on the surface, and nest refuse is often richer in nutrients than the surrounding soil. Neither benefit depends on how far the seed travels, which may explain why plants go on producing the attachment even though ants carry seeds such short distances.
According to the passage, why did biologists come to doubt that distance is the main benefit to the plant?
The question points to the sentences about distance. Find the first view ("Biologists first assumed that the plant's gain was distance") and read on.
The next sentence begins with "But", the turn: ants rarely carry seeds more than a few metres, a trivial distance compared with wind and bird dispersal.
Answer in your own words: because the distances ants achieve are tiny compared with other ways seeds travel.
Answer
Because ants carry seeds only a few metres, which is trivial next to the distances that wind or birds achieve. A tempting wrong answer is "because seeds are hidden from rodents": that is one of the benefits now thought more important, not the reason distance was doubted.
Example 2: An inference question
Using the same passage, which statement can be inferred?
- Plants whose seeds are carried by ants produce more seeds than other plants.
- If ants left seeds on the surface far from any nest, the plant would lose at least one of the benefits the passage calls most important.
- Ants eat the seeds they carry when food is scarce.
Statement 1: the passage says nothing about how many seeds such plants produce. Out of scope.
Statement 2: one of the two important benefits is that seeds buried in a nest are hidden from rodents that eat seeds left on the surface. A seed left on the surface far from a nest would not have that protection. The statement follows in one step and says only "at least one", which is as strong as the text allows.
Statement 3: the passage says the seed is discarded "undamaged". Nothing is said about scarcity, and the claim runs against the text.
Answer
Only the second statement can be inferred. Note how modest it is: it does not claim the plant would gain nothing, only that it would lose the rodent protection, and possibly the nutrient benefit too.
Common traps
Answering from memory
After one read, it is tempting to answer a detail question from what you remember. Memory blends nearby sentences, and wrong choices are built from those blends. Go back to the sentence every time; it takes seconds.
The choice that copies the passage’s words
Exact wording from the passage is not a sign of a right answer. Wrong choices often lift a phrase from one sentence and attach it to a claim from another. Check that the meaning, not just the vocabulary, matches.
Inferring what is only possible
A passage that says "some species returned" leaves open whether most did. A choice that is consistent with the passage is not therefore inferred. Ask whether the passage would be contradicted if the choice were false; if not, the choice is not an inference.
Half-right choices
A choice with two clauses, one supported and one not, is wrong. Readers who nod at the first clause often stop reading. Check every clause.
Check yourself
Answer each question before you open its answer.
Question 1: Why a bottleneck is different
Reading Comprehension
When a city adds a lane to a road to relieve congestion, travel times often improve at first and then drift back towards their old level within a few years. Transport researchers call this induced demand. The extra capacity makes driving cheaper in time, so people who previously travelled at other hours, by other routes or by other means begin to drive at peak hours, and some who did not make the trip at all now do. The effect is not universal. Where a road was congested because of a single bottleneck, such as a narrow bridge, widening that point can produce lasting gains, because the extra traffic it attracts is held back by limited capacity elsewhere on the network. Critics of road building sometimes overlook this distinction, but its practical reach is modest: most urban congestion, the researchers argue, is spread across whole networks rather than concentrated at single points.
According to the passage, widening a single bottleneck can produce lasting gains because
- A.bottlenecks are usually found on bridges
- B.drivers do not change their habits when a bottleneck is removed
- C.induced demand does not occur on roads that cross bridges
- D.most urban congestion is concentrated at single points
- E.the extra traffic it attracts is limited by the capacity of other parts of the network
Show the answer
Answer: E. the extra traffic it attracts is limited by the capacity of other parts of the network
Working
The sentence about bottlenecks gives the reason after "because": "the extra traffic it attracts is held back by limited capacity elsewhere on the network". The right choice paraphrases exactly that.
Why the other options are wrong
- A. A narrow bridge is given only as an example of a bottleneck; the passage does not say most bottlenecks are bridges, and that would not explain the gains anyway.
- B. The passage says widening a bottleneck does attract extra traffic; the point is that the traffic is limited elsewhere, not that habits stay the same.
- C. Nothing says induced demand is absent; the passage says the traffic it brings is held back by capacity elsewhere.
- D. This reverses the researchers' claim, which is that most congestion is spread across networks.
What carries over
In a detail question, find the "because" in the passage; the answer is its paraphrase.
Question 2: How the author weighs the critics’ oversight
Reading Comprehension
When a city adds a lane to a road to relieve congestion, travel times often improve at first and then drift back towards their old level within a few years. Transport researchers call this induced demand. The extra capacity makes driving cheaper in time, so people who previously travelled at other hours, by other routes or by other means begin to drive at peak hours, and some who did not make the trip at all now do. The effect is not universal. Where a road was congested because of a single bottleneck, such as a narrow bridge, widening that point can produce lasting gains, because the extra traffic it attracts is held back by limited capacity elsewhere on the network. Critics of road building sometimes overlook this distinction, but its practical reach is modest: most urban congestion, the researchers argue, is spread across whole networks rather than concentrated at single points.
It can be inferred that the author regards the critics' failure to distinguish bottlenecks from other congestion as
- A.the main reason that road-building schemes fail
- B.a deliberate misrepresentation of the research
- C.a real error, but one that matters for relatively few urban roads
- D.an error that undermines the theory of induced demand
- E.a correct judgement that the researchers wrongly dispute
Show the answer
Answer: C. a real error, but one that matters for relatively few urban roads
Working
"Overlook" shows the author thinks the critics miss a real distinction, so it is an error. "Its practical reach is modest", followed by the claim that most congestion is spread across networks, shows that the exception covers few cases. Together: a real error that matters for relatively few roads.
Why the other options are wrong
- A. The passage explains failing schemes by induced demand, not by anything the critics do.
- B. "Overlook" describes an oversight, not deliberate misrepresentation.
- D. The bottleneck case is an exception the theory itself explains, through capacity elsewhere; it does not undermine the theory.
- E. The author says the critics "overlook" the distinction, which treats it as a real distinction they miss, not as their correct judgement.
What carries over
An inference about the author’s view combines the author’s own evaluative words; here "overlook" gives the error and "modest" gives its size.
Question 3: Applying the passage to a new case
Reading Comprehension
When a city adds a lane to a road to relieve congestion, travel times often improve at first and then drift back towards their old level within a few years. Transport researchers call this induced demand. The extra capacity makes driving cheaper in time, so people who previously travelled at other hours, by other routes or by other means begin to drive at peak hours, and some who did not make the trip at all now do. The effect is not universal. Where a road was congested because of a single bottleneck, such as a narrow bridge, widening that point can produce lasting gains, because the extra traffic it attracts is held back by limited capacity elsewhere on the network. Critics of road building sometimes overlook this distinction, but its practical reach is modest: most urban congestion, the researchers argue, is spread across whole networks rather than concentrated at single points.
The passage most strongly supports which of the following about adding a lane to a congested urban road where the congestion is spread across the whole network rather than caused by a single bottleneck?
- A.Travel times would likely improve at first and then drift back towards their earlier level.
- B.Travel times would fall permanently.
- C.Travel times would immediately become worse than before.
- D.Fewer trips would be made on the road at peak hours.
- E.People would no longer change the times at which they travel.
Show the answer
Answer: A. Travel times would likely improve at first and then drift back towards their earlier level.
Working
The general pattern of induced demand is stated in the first sentence: improvement at first, then a drift back. The only exception the passage names is the single bottleneck, and the case in the stem is explicitly not that. So the general pattern applies.
Why the other options are wrong
- B. Lasting gains are what the passage expects only at a single bottleneck; this case is the opposite one.
- C. The passage says travel times improve at first; nothing suggests an immediate worsening.
- D. This reverses induced demand: the new capacity draws more people to drive at peak hours.
- E. The passage says people who travelled at other hours start to drive at peak hours, so travel times do change.
What carries over
When a passage states a rule and one exception, a case outside the exception falls under the rule.
Key points
Detail answers are paraphrases of a sentence you have just reread.
An inference must be forced by the passage, not merely allowed by it.
Match the strength of a choice to the strength of the text; reject half-right choices.
Contrasts and exceptions tell you what the passage implies about the other case.
All questions here are original and written for UniExamer; none comes from the test maker.
Written by the UniExamer team with AI assistance. Every worked example and check question was re-solved by an independent checker before publication. No subject expert has reviewed this lesson yet. If you find a mistake, write to support@uniexamer.com.