Reading Comprehension and Passage Inference

June Huh Fields Medal biography

Logical inference questions ask which statement must be true given the premises, so the decisive skill is reading quantifiers exactly. A fact about one individual who belongs to a category supports only an existential conclusion, namely that at least one member of that category has the property. It never supports a universal conclusion about every member. If one known holder of a prestigious award is also a college dropout, then some holders of that award are college dropouts.

Quantifier words control the scope of a claim. 'Some' means at least one, and a single case satisfies it. 'Every', 'all', and 'everyone' require the property to hold for each member without exception, so one counterexample refutes them. A universal claim about a group is therefore falsified by a single named member who lacks the feature.

A negative fact about one member is especially useful in these questions. If a person is recorded as not having won a competition that the group's members are said to win, then any statement that all members won it must be rejected.

Converse errors are the most common trap. A rule such as 'everyone who has property X also has property Y' does not allow the reverse, 'everyone with Y has X', because the premise links X to Y in one direction only. Accepting the reverse is an invalid inference.

Background details about a person's past, such as an early hobby, describe that person only. Unless the passage states a general rule, such details cannot be stretched into a claim about all members of a category.

Key terms:

• some — at least one; written \exists x. 'Some medalists are poets' is true if one medalist is a poet.
• every / all / everyone — each member without exception; written \forall x. One exception makes the claim false.
• converse error — reversing 'if X then Y' into 'if Y then X'.
• overgeneralisation — extending a single case to the whole class.
• irrelevant detail — a past fact that does not create a present rule.

Example: Ana won a national chess title and once trained as a pianist. It follows that some national chess champions have trained as pianists. It does not follow that all national chess champions have trained as pianists.

Sri Lanka economic crisis and World Bank reforms

Passages about institutions and crises depend on small conditional words, and words such as 'until', 'unless', and 'only if' decide what can be inferred. When an organisation withholds an action until a condition is met, the passage implies that the condition is not met at the time of writing. This inference is certain because the withholding is stated as a present situation.

A second skill is separating a cause from its consequence. A passage may say that deep underlying problems have caused a shortage, which makes the shortage an effect and not the root cause. An option that names the shortage as the root cause reverses the stated relation and is wrong.

Policy vocabulary also matters. Structural reforms change the basic rules and institutions of an economy, while economic stabilisation aims at short-term control of prices, inflation, and external balances. A passage that says a government should adopt reforms does not state that an outside body will advise that government on them.

To repurpose resources means to redirect money that has already been committed to a new use. It is not the same as providing additional funds, so an option that promises new money goes beyond the text.

Key terms:

• until — marks the point at which an action begins; 'They will not sign until the audit is complete' implies that the audit is not yet complete.
• root cause — the underlying reason; a symptom such as a shortage is not the root cause.
• repurpose — redirect existing resources to a different use.
• alleviate — make a problem less severe; it does not mean eliminate.
• adequate — sufficient for a purpose; a condition stated with 'until' implies that the current state is not yet adequate.

Example: The council will not raise wages until productivity improves. Therefore productivity has not yet improved. The council might raise wages later, but that possibility is not stated with certainty.

Climate change and rice production

Passages about threats and responses use modal verbs and adjectives that signal how strongly a claim is supported. 'Will' states a prediction, 'may' states a possibility, and 'could' states a capacity. A passage that describes a new crop variety under development supports only the claim that it may be used in response to a problem. It does not license the claim that it will replace the existing crop.

'Resilient' means able to withstand stress and keep functioning. A resilient crop continues to produce under harsh conditions; it is not restricted to growing only under those conditions. Restricting an adjective to a narrow setting is a common distractor.

Yield and quantity must be read carefully. Higher yield means more output per unit of land, so a claim that the output is smaller than another variety's is contradicted when the passage states that yields are higher.

A threat to 'sustained availability' means that supply may not be maintained over time. A threat to a product does not establish that the same product will keep giving good output under the same conditions; such a claim must be checked against what is stated.

Key terms:

• resilient — able to withstand or recover from stress.
• sustained — maintained over a long period.
• adverse effect — a harmful consequence, such as crop loss caused by drought.
• alternative — a substitute; a response that may be used is not necessarily an alternative that replaces what exists.
• lesser / fewer — 'lesser' is used in formal writing with uncountable quantities such as the amount of produce, while 'fewer' is used with countable nouns.

Example: The new drug may reduce the risk of infection. It is therefore possible, but not certain, that the drug will prevent infection in all patients.

Tobacco cessation advice survey

When two percentages are both measured against the same total population, the question is really about how two groups overlap. Let A be the group advised to quit and B the group that tried to quit, both drawn from the same population. The data fix only the sizes |A| and |B|, so what can be concluded depends on the bounds of the intersection |A \cap B|, not on exact values. A conclusion is logically certain only if it holds in every arrangement of the groups that is consistent with the data, which is what the phrase 'logically inferred with certainty' demands. If even one consistent arrangement breaks a claim, the claim cannot be inferred.

Two bounds decide most such questions. The overlap can never exceed the smaller group, so |A \cap B| \le \min(|A|, |B|). The part of A that lies outside B is at least |A| - |B|, which gives a lower bound on the members of A who did not attempt. A majority means more than half of a group, so a majority of A did not attempt whenever |A| - |B| > \frac{1}{2}|A|, that is, whenever |B| < \frac{1}{2}|A|.

The converse does not hold. A majority of A attempting cannot be shown from the data, because the attempters may all lie outside A, and no positive lower bound on |A \cap B| follows when |A| + |B| does not exceed the total.

Attempting something and succeeding at it are different events. A passage that reports attempts says nothing about success unless it states a success figure, and a percentage of one group cannot be transferred to another group. A share of users who were advised is not a share of users who quit.

• majority — more than half of a group, not just a large number. e.g. If 40 of 70 students passed, the passing students form a majority of the 70.
• approximately — roughly equal to; a figure marked 'approximately' is compared with the bound allowing a small rounding margin. e.g. 0.46 is approximately 46 percent.
• at least / at most — a lower or upper limit that holds whatever the arrangement. e.g. If 40 percent were warned and 25 percent acted, at least 15 percent were warned but did not act.
• with certainty — true in every possible case consistent with the text, not merely likely.

Cancer metaphors and modern illness

Writing about disease relies heavily on figurative language, and the images used for cancer have changed along with biology. A metaphor asserts that one thing is another without the words 'like' or 'as'; figurative language is the wider category that includes metaphor, simile and idiom. Describing a cell as a machine is a metaphor, since a cell is not literally a machine, but the image helps explain how parts cooperate and how signals start or stop activity.

When a disease is described through an image of runaway growth, a loss of control or a self-operating device, the image reflects the technology and the concerns of the period in which it is used. The passage's reasoning that cancer seems modern because its metaphors are modern is an example of this link between imagery and era.

When a question asks which option does NOT describe a passage or follow from it, the target is the option that contradicts the text or goes beyond it. Absolute words such as 'never', 'always', 'all' and 'none' are warning signs, because an absolute claim is easily refuted by a single counterexample in the text. A paraphrase that restates the text is usually correct as a description, so it is not the answer.

• metaphor — a figure of speech that identifies one thing with another. e.g. The city is a jungle at rush hour.
• figurative language — words used beyond their literal sense, such as metaphor or simile. e.g. Calling a rumour a spark is figurative language.
• automaton — a self-operating machine, or a person acting mechanically. e.g. The guard moved through the corridor like an automaton.
• quench — put out, satisfy or stop something. e.g. A thick blanket can quench a small fire.
• indestructible — incapable of being destroyed. e.g. The old coin seemed almost indestructible.
• tip into — slide or fall into a state. e.g. The market tipped into a sharp decline.
• reflect — show or mirror a condition or attitude. e.g. The budget reflects the government's priorities.

Oxpecker and rhino symbiosis

Symbiosis is a close and long-lasting relationship between two species. Biologists classify it by the outcome for each partner. In mutualism both partners benefit; in commensalism one benefits and the other is unaffected; in parasitism one benefits at the other's expense. An interaction in which a bird feeds on the pests living on a large mammal is usually described as mutualistic, because the mammal also gains by losing those pests.

In such a relationship the question is which benefit is primary, meaning the main or most direct gain. For the bird, the main gain is usually food, because the pests on the host are its prey. For the host, the benefit can be removal of parasites, and some birds also give alarm calls when danger approaches. Alarm calls are often reported as protective, but whether they reliably save the host is a claim that should be phrased with 'may' rather than 'will'.

When answer options pair two organisms with two benefits using 'respectively', the items must match in the order named. Check each pairing separately: a choice may describe the correct benefit for one partner while giving the wrong benefit or no benefit for the other, and a choice that reverses the roles of the species fails even if one of its phrases is accurate.

• symbiosis — a close, long-term interaction between two species.
• mutualism — a symbiosis in which both partners gain. e.g. Cleaner fish feed on parasites and gain food, while the larger fish is freed of parasites.
• commensalism — a symbiosis in which one partner gains and the other is unaffected. e.g. Barnacles attach to a whale and gain transport, without harming the whale.
• parasitic — living on or in another organism and harming it. e.g. Ticks are parasitic on the animals they feed on.
• habitat — the natural environment where an organism lives. e.g. Coral reefs are the habitat of many small fish.
• poacher — a person who hunts or kills animals illegally. e.g. Park rangers patrol to stop poachers.
• respectively — in the order mentioned, so each item is matched to the item listed in the same position.
• may / will — 'may' signals a possibility, while 'will' signals a certainty.

DNA information and protein synthesis

DNA stores information as a linear sequence of four nucleotides, usually abbreviated A, T, C and G. The sequence is not used uniformly. Coding regions are read in groups of three nucleotides, called codons or triplets, and each group specifies one amino acid. Amino acids are then linked in order to synthesize a protein.

The remainder of the genome is non-coding in the sense that it does not specify amino acids. A region that does not code for protein is not thereby unimportant, since non-coding DNA can contain regulatory sequences that control when and how much a gene is expressed. Therefore 'does not code for amino acids' and 'has no role in protein synthesis' are different claims, and only the first can be read directly from a passage that defines coding regions.

A statement about the state of scientific knowledge, such as whether a function is understood, is a claim about what is known. A passage can be silent on it, and silence does not establish either that the function is understood or that it is unknown. Such statements cannot be inferred with certainty from a passage that does not address them.

When two statements are given as (i) and (ii), each must be checked independently. The answer 'neither (i) nor (ii)' is correct when neither statement follows with certainty, even if both sound plausible.

• nucleotide — a building block of DNA, consisting of a base, a sugar and a phosphate group.
• codon — a group of three nucleotides that specifies one amino acid or a stop signal.
• coding region — a stretch of DNA whose sequence is read to make amino acids.
• non-coding region — a stretch of DNA that does not specify amino acids.
• synthesize — to make a substance through a chemical process. e.g. Cells synthesize proteins from amino acids.
• regulatory — controlling or adjusting how another process proceeds. e.g. A regulatory sequence can switch a gene on or off.
• neither ... nor — means that both alternatives fail. e.g. Neither the first claim nor the second follows from the text.

Rehearsal and public speaking preparation

The phrases 'no less ... than' and 'no more ... than' express equality, not ranking. 'No less important than' means that two things are equally important, so neither is ranked above the other. For example, 'Practice is no less essential for a surgeon than for a pilot' places the two professions on the same level of need. Learners often confuse this with 'less important than', which places the first item below the second. Similarly, 'no more ... than' means equal in a low degree, as in 'A nervous speaker is no more relaxed than a nervous actor.' Such phrases are common in reading passages, where a writer first gives examples and then extends the same claim to a new group.

To rehearse means to practise a performance in advance so that it runs smoothly. In an argument, a writer may list groups that already do something, then argue that a third group should do the same. The contrast marker 'on the other hand' signals that the writer is turning from one view to an opposing one, and expressions such as 'I find it strange that' show the writer's evaluation rather than a fact. A statement is true only if the text supports it directly or it necessarily follows from the text. Adding the word 'only' to a claim, as in 'more important only for musicians', turns a balanced statement into an overclaim that the text does not make.

Readers should also reject statements that compare two groups which the text never compares. If a passage says nothing about how actors and musicians rank, a statement about their relative importance is unsupported, even if it sounds plausible.

Genetically modified mosquito control

Modal verbs signal the strength of a claim. 'Is' and 'shows' state facts; 'may', 'might' and 'could' state possibilities. The sentence 'A method may have undesired consequences' means that a risk is possible but not proven, and it does not mean that the method is dangerous or harmful in every case. The same logic applies to 'The drug may cause drowsiness', which does not establish that it causes harm to all patients. A reader should keep the strength of the modal in mind when choosing an inference.

• remains to be seen — it is not yet known whether something will happen. Example: Whether the new policy will lower costs remains to be seen. The phrase describes an open question, so it cannot be turned into a claim of safety or of danger.
• unforeseen — not predicted in advance. Example: The project was delayed by unforeseen problems in the supply chain.
• it is not clear whether — evidence is missing or insufficient. This is different from proof that something does not exist.

A central rule of inference is that an unknown outcome cannot be used as a known fact. If a passage says that the consequences of a new approach are still unknown, a conclusion that the approach has no side effects, or that it is dangerous, goes beyond the text. Only the claims that are actually stated may be combined. Absolute words such as 'no', 'any', 'always' and 'cannot' make a claim much stronger, so they need explicit support in the passage.

Urban heritage and crooked streets

Several verbs in this kind of passage describe actions on buildings and streets, and their meanings must be known exactly.

• pull down — demolish or tear down. Example: The council plans to pull down the old warehouses by the river.
• do away with — eliminate or abolish. Example: The city did away with the tram network in the 1960s.
• crooked — not straight; winding or bent. Example: The old town is full of crooked lanes.
• hurt no man — cause no harm to anyone. Example: The rule hurts no one, so few people object to it.

When a writer says that someone wonders why an action is taken, the wondering is an expression of puzzlement, not an activity the writer enjoys. Phrases such as 'which are my delight' attach the emotion to the object named, here the streets, not to a different action. Reading the grammar carefully prevents a common error in which an attitude is assigned to the wrong element of the sentence.

'One or another' means 'some one of a set', so it does not claim that every member of the set is affected. If a passage says that some of several buildings are being demolished, it does not follow that all of them are. 'Every day' describes a recurring activity, and it still does not extend the scope beyond the group named.

Metaphors such as 'life-channels' (main routes that keep a city moving) and 'islands of the past' (surviving old areas amid new development) carry meaning beyond their literal sense. Phrases such as 'it ought to be enough' express the writer's opinion about what should happen, so a statement that the writer does not express cannot be marked as true.

Anti-obesity measures and income inequality

The adverb 'superficially' means at the surface level, dealing only with visible effects and not with underlying causes. A policy that treats the outward symptom of a problem without changing its origin is a superficial response. For example, a campaign that asks people to eat fewer snacks, while leaving the causes of low incomes untouched, may be described as treating the problem superficially. A summary question asks for the main claim of the passage, so the correct option must keep the writer's conclusion and must not add predictions such as 'likely to succeed' that the passage does not make.

• sidestep — avoid dealing directly with something. Example: The minister sidestepped questions about the budget deficit.
• core problem / root cause — the underlying origin of a problem, as opposed to its visible result.
• address — deal with a problem directly, which is different from merely being near it.

A measure that 'sidesteps' the core problem does not address it. Answer options that say the proposal 'addresses the core problems' contradict a passage that says it avoids them, even if the option uses the same vocabulary.

The causal direction is a frequent trap. If a passage says that poverty and inequality cause obesity, an option stating that obesity causes poverty reverses the relationship and is not supported. Readers should identify the cause and the effect before judging an inference.

Computers and AI in society

The adjective 'ubiquitous' means present everywhere, or found in almost all places. A statement that computers are ubiquitous supports the claim that they are present in almost all places, but it does not say that they are present in every single place. Similarly, 'used to improve efficiency in almost all fields' supports a claim about wide use, not a claim about universal use.

To 'deduce' means to reach a conclusion that follows necessarily from the information given. When a passage mentions both benefits and costs, a statement that the effects are both positive and negative for people can be deduced, provided that both are actually mentioned. Phrases such as 'both ... and' show that two opposite effects are stated together.

The construction 'AI enables computers to learn, given enough training data' is a conditional. The ability to learn depends on the condition stated after 'given'. Therefore, a statement that AI can be done without data is not supported, because the passage makes the learning ability conditional on data. Statements that use absolute words such as 'cannot' are rarely deducible unless the passage states the same absolute claim.

Leafy vegetable consumption and healthy lifestyle

The phrase 'is a clear indication of' means that one fact is strong evidence for another. An indication is a sign, not a proof, and the word 'clear' expresses confidence in the sign. When a sentence says that a change in one behaviour is a clear indication of a healthy lifestyle, it presents a link between the two, so the link is part of what the sentence presupposes. A presupposition is something a sentence takes for granted, and it can be inferred because the sentence cannot be understood without it.

The article 'an' in 'an indicator' allows that there may be other indicators, whereas 'the only indicator' excludes all others. A statement that describes one fact as an indicator does not claim that it is the only indicator, so a conclusion that it is the only one cannot be drawn. Likewise, a claim that another factor is 'not the only' indicator is not established by the sentence unless it is directly mentioned.

'Increased in recent months' compares a recent period with an earlier one; it describes a change, not an absolute level. An increase does not reveal how much was consumed before. Any option that introduces a topic the sentence never mentions, such as awareness of health hazards from another food, is unsupported, however reasonable it may sound.

Genetic mutation and lactose digestion

When a reading passage is followed by a question asking what can be inferred, the correct option must follow logically from what the passage actually says. An inference is not a fact that is merely true in the real world, nor a guess that sounds reasonable. It is a conclusion forced by the text, so the reader should check each option against the exact scope and wording of the passage.

The most common trap concerns quantifiers. Words such as some, certain, a number of, and a particular group limit a claim to part of a population. A statement about some members of a group cannot be extended to the whole group, so options that speak of all human beings or of no human being are excluded even when they sound like a neat contrast.

Another key point is the difference between a stated link and an unstated requirement. If a passage says that a trait arose from a change in a gene, one may infer that, in those individuals, the trait resulted from that change. It does not follow that the trait is necessary for everyone or that it is essential to the species. Options that introduce a necessity the text never mentions are unsupported.

Useful expressions:

• attribute A to B — to regard B as the cause or source of A. e.g. The delay was attributed to a faulty sensor.
• result from — to be caused by something. e.g. The crack resulted from repeated heating.
• essential — absolutely necessary; stronger than useful or helpful. e.g. Oxygen is essential for combustion.
• contradict — to state the opposite of a claim, so that both cannot be true. e.g. The new data contradicted the earlier report.

When checking an option, first decide whether it is stated, implied, contradicted, or not addressed at all. Only an option implied by the text can be correct in a can-be-inferred question, so an option the passage does not address should be rejected.

Life of a solitary scholar

Many reading passages describe a person's life without naming the event that defines the passage, so the reader must rely on clues such as the title, the tense of the verbs, and the words used for illness or loss. A passage that reads like a tribute at a funeral, is written in the past tense, and mentions a fatal illness indicates that the person described has died. Such a conclusion is an inference from genre and wording rather than from a direct statement.