Future Challenges

Respuesta correcta: C) exacerbate

• A) alleviateIncorrect. 'Alleviate' means to make something less severe, which is the opposite of what's needed.
• B) mitigateIncorrect. 'Mitigate' means to make something less severe, which doesn't fit the negative consequence implied.
• C) exacerbateCorrect. 'Exacerbate' means to make a problem or bad situation worse, which fits perfectly here.
• D) facilitateIncorrect. 'Facilitate' means to make an action or process easy or easier, which is not appropriate for a social divide.

Respuesta correcta: D) surge

• A) plateau'Plateau' means to level off at a stable value, and nothing in the sentence suggests the demand stops rising. The clause about heat stored in asphalt predicts continued growth, not stability.
• B) wane'Wane' means to become gradually weaker or less, which is the opposite direction. The sentence describes cities with more of a particular problem, and the cause given increases rather than reduces it.
• C) stabilise'Stabilise' means to become steady after change, and the projection is of continuing growth. Reading stabilisation here contradicts the causal clause the writer supplies to justify the forecast.
• D) surge'Surge' means to rise suddenly and sharply, and the sentence forecasts a steep increase in demand driven by an environmental mechanism. The magnitude implied by 'expected to' and the cause given both point to a sharp rise rather than a gradual one.

Respuesta correcta: D) aggravate

• A) defuse'Defuse' means to remove the danger from a situation, and nothing in the sentence suggests the hazard was neutralised. The runoff reaching a new area is the opposite of defusing anything.
• B) circumvent'Circumvent' means to go around a problem, and the sentence describes solving one location by displacing the difficulty, not avoiding the obstacle. The word names a route, not a worsening.
• C) pre-empt'Pre-empt' means to act before a problem occurs, and the sentence reports what happens after the barriers are built. Nothing here describes action taken in advance of the flood.
• D) aggravate'Aggravate' means to make a situation worse, and the sentence describes infrastructure that transfers damage rather than preventing it. The clause about water arriving elsewhere supplies the mechanism that makes this worse, not better.

Respuesta correcta: C) undermine

• A) vindicate'Vindicate' means to clear someone of blame or prove a claim right, and nothing in the sentence justifies or clears anything. The outcome described is the opposite: the money bought nothing usable.
• B) consolidate'Consolidate' means to strengthen or combine into a more solid whole, and the sentence describes equipment going unused rather than being put to work. Nothing here builds on the initial purchase.
• C) undermine'Undermine' means to weaken something from below, which is what unused hardware does to a programme bought with public money. The clause about the tablets ending up in cupboards shows the investment failing quietly rather than visibly.
• D) leverage'Leverage' means to use something to maximum advantage, and the sentence states the opposite: the devices were never used at all. A word for effective exploitation cannot describe abandonment.

Respuesta correcta: C) Colombia's ageing population is a challenge that requires action now.

• A) Colombian families are bigger than they were in the past.The text says families are smaller than in the past, which is one of the causes of the ageing population.
• B) Most retired Colombians already live in poverty.The text uses 'could face poverty', which is a future risk, not a description of the present situation.
• C) Colombia's ageing population is a challenge that requires action now.The text describes the change (more people over 60), the risk (fewer workers, poverty) and the solution economists propose 'now'.
• D) Older Colombians should continue working with informal contracts.The economists recommend more formal employment, because informal workers do not contribute to pensions.

Respuesta correcta: B) Workers will need new skills to keep their jobs in the future.

• A) The port will close before 2030.The manager talks about jobs changing in 2030, which means the port will still exist and need workers.
• B) Workers will need new skills to keep their jobs in the future.He says future jobs will be different, and the company offers courses in electronics and maintenance, which suggests workers must learn new skills.
• C) Many workers were fired this year.The manager says 'Nobody is being fired this year', the opposite of this option.
• D) The automatic cranes are slower than people.The text says the cranes move containers 'faster than ever'.

Respuesta correcta: B) can't have been working

• A) must have been workingMust have been working expresses a strong positive deduction, which conflicts with the absence of the required battery.
• B) can't have been workingCan't have been working expresses a strong negative deduction about the past, supported by the missing essential battery.
• C) should have been workingShould have been working expresses an expectation rather than the deduction that operation was impossible without a battery.
• D) may have been workingMay have been working leaves operation possible, but the stated requirement and empty compartment rule it out.

Respuesta correcta: D) Repair leaks in its water pipes.

• A) Build a new reservoir next to Chingaza.The text does not mention building any new reservoir; the experts' recommendation is about the pipes.
• B) Continue rationing water permanently.Rationing is described as a past measure. The experts propose a different solution for the future.
• C) Stop treating water in the city.Treated water is mentioned because it is wasted through leaks; nobody suggests stopping treatment.
• D) Repair leaks in its water pipes.The experts 'warn that the city must reduce leaks in its pipes' before the next dry period, which is exactly what this option says.

Respuesta correcta: A) Someone might have deleted the file accidentally.

• A) Someone might have deleted the file accidentally.Might have deleted presents accidental deletion as a possible past explanation without claiming that the evidence proves it.
• B) Someone must have deleted the file accidentally.Must have deleted expresses a strong deduction, but the team lacks evidence establishing deletion as the explanation.
• C) Someone can't have deleted the file accidentally.Can't have deleted rules accidental deletion out, whereas the available information does not exclude it.
• D) Someone should have deleted the file accidentally.Should have deleted expresses an expectation or judgment about an action, not a tentative explanation for the missing file.

Respuesta correcta: C) To encourage students to register for a youth forum.

• A) To report the results of a city council meeting.The city council is mentioned only as the place where proposals will be presented in the future; no meeting results are reported.
• B) To explain how climate change affects Manizales.Climate change is one topic of the forum, but the text gives no information about its effects on the city.
• C) To encourage students to register for a youth forum.The text addresses young readers directly ('Are you...?', 'Join'), gives the conditions and ends with an instruction to register before a deadline.
• D) To announce new jobs for scientists and business leaders.Scientists and business leaders are participants in the discussions, not people being offered jobs.

Respuesta correcta: C) had

• A) hasIncorrect. The sentence refers to a past sequence, requiring the past perfect in inversion.
• B) wasIncorrect. 'Was' does not fit the past perfect structure required by 'Hardly'.
• C) hadCorrect. 'Hardly had...' is a classic C1 inversion structure used for sequential events.
• D) didIncorrect. 'Did' would require the base form of the verb, not the past participle 'been'.

Respuesta correcta: B) did

• A) had'Had' would form a past perfect and need the participle 'accepted', placing the acceptance before another past point. The sentence describes the moment the committee changed its position.
• B) did'Not until' is a fronted negative that inverts the main clause, and 'did' carries the simple past: 'not until three studies were published did the committee accept'. The main verb returns to its base form 'accept'.
• C) would'Would' belongs to a conditional or reported structure, and no condition or reporting frame is present. The clause states a completed past decision, which takes a finite past auxiliary.
• D) must'Must' expresses obligation or deduction about the present, and the clause is about the past. Nothing in the sentence requires an obligation or supports a deduction about now.

Respuesta correcta: B) Ana strongly deduces that a warning occurred, while Luis says a warning was the appropriate past action.

• A) Both speakers state that the warning was impossible.Neither must have nor should have expresses impossibility; a negative deduction would use can't have.
• B) Ana strongly deduces that a warning occurred, while Luis says a warning was the appropriate past action.Must have warned conveys a strong past deduction; should have warned evaluates what ought to have been done, often implying it was not done.
• C) Ana describes a future requirement, while Luis describes a present habit.Both statements use have plus a past participle and concern a past warning, not a future requirement or present habit.
• D) Ana criticizes a missed duty, while Luis strongly deduces that the warning occurred.This reverses the usual meanings: must have expresses the deduction, while should have expresses the expected or appropriate action.

Respuesta correcta: A) did

• A) did'Only after' fronted inverts the main clause, and 'did' carries the simple past: 'only after the plant was decommissioned did the supply fail'. The main verb returns to its base form 'fail'.
• B) had'Had' would form a past perfect and need the participle 'failed', placing the failure before another past point. The sentence reports the failure as an event in its own right.
• C) should'Should' expresses obligation or expectation about the present or future, and the clause is about a past event already completed. Nothing in the sentence looks forward from the present.
• D) might'Might' would present the failure as a possibility, but the sentence asserts that it happened. The word 'and the cause was never properly investigated' confirms a fact rather than a hypothesis.

Respuesta correcta: A) does

• A) does'Seldom' inverts the clause, and 'does' carries the present with the singular subject 'a government'. The main verb 'acknowledge' stays in its base form, as it must after 'does'.
• B) do'Do' is the plural auxiliary, but the subject 'a government' is singular. The inversion has moved that subject to the right of the auxiliary without altering its number.
• C) did'Did' would put the observation in the past simple, but the sentence describes what governments in general do. A recurring present pattern takes the simple present under inversion.
• D) had'Had' would form a past perfect and require the participle 'acknowledged', placing the acknowledgement before another past point. The clause makes a general claim about present practice.

Respuesta correcta: B) Camila must have entered the shelter; she might have repaired the radio.

• A) Camila might have entered the shelter; she must have repaired the radio.The log directly supports her entry, but it provides no evidence that she repaired the radio, so the certainty levels are misplaced.
• B) Camila must have entered the shelter; she might have repaired the radio.The entry record supports a strong deduction about entering, while repairing the radio remains only a possible unrecorded activity.
• C) Camila can't have entered the shelter; she might have repaired the radio inside.Can't have entered contradicts the access record that explicitly places Camila at the entrance at 18:05.
• D) Camila must have entered the shelter; she must have repaired the radio.The record supports entry but says nothing about activities inside, so it cannot support a strong deduction about radio repairs.

Respuesta correcta: C) The current strategy is directed towards the wrong objective.

• A) They are literally looking for something in the trees of Manizales.Incorrect. This is a literal and incorrect interpretation of the idiom.
• B) The approach is too noisy and aggressive.Incorrect. The idiom relates to direction/objective, not volume or attitude.
• C) The current strategy is directed towards the wrong objective.Correct. This idiom means to follow a wrong line of thought or course of action.
• D) A new environmental project involving trees should be started.Incorrect. This misinterprets the figurative meaning of the phrase.

Respuesta correcta: A) Natalia may be taking on more responsibilities than she can handle.

• A) Natalia may be taking on more responsibilities than she can handle.'Bite off more than you can chew' means to accept more work than you can manage; Tomás reacts to the three big tasks she lists for one month.
• B) Natalia should eat less before the exam.This reads 'bite' and 'chew' literally. The conversation is about her activities, not about food.
• C) Natalia is not ambitious enough.Tomás warns her about doing too much, which is the opposite of saying she is not ambitious.
• D) Natalia must cancel the science fair immediately.Tomás gives a general warning ('Be careful'); he does not tell her which activity to cancel.

Respuesta correcta: A) She is naming a common pattern while explicitly refusing to present it as proven evidence.

• A) She is naming a common pattern while explicitly refusing to present it as proven evidence.The final clause separates an observation from a finding she can demonstrate. She asserts that the pattern is repeated and simultaneously limits how much authority it carries, which is what the two phrases do together.
• B) She is retracting a claim she had already proved.A retraction would state that a proven claim proved false. Here she is qualifying a claim she never presented as established, so the direction of the statement is not reversed.
• C) She is demanding that the other speakers bring their own plans.The final clause describes what she is doing with her own statement. There is no imperative, no question and no reference to anyone else's documents in the quotation.
• D) She is insisting the three projects are wasteful.The sentence says the plans fund the same three projects, which is an observation about repetition, not a judgement that the spending is wasteful. No evaluative label appears anywhere in the quotation.

Respuesta correcta: D) Everyone to share the same understanding before deciding.

• A) Everyone to read the same page of the report.This takes the idiom literally. The moderator is talking about the meaning of a term, not about a page in a document.
• B) The group to vote immediately.'Before we vote' shows the moderator wants a step first, so an immediate vote is the opposite.
• C) Each person to write a different definition.Different definitions would create disagreement, which is what the moderator wants to avoid.
• D) Everyone to share the same understanding before deciding.'Be on the same page' means to agree on or understand something in the same way; the moderator wants a shared definition of 'sustainable mobility' before the vote.