Casa ESL · C1 Advanced · Teacher's Resource
Answer Key Booklet
All 20 units · Steps 1 & 2 · For teacher use only. Do not distribute to students.
Step 1 — Units 1–10
Unit 01
Academic Discourse
Exercise 11. discovery · 2. acquisition · 3. improvement · 4. assumption · 5. stability
Exercise 21. The committee's thorough investigation of the incident… · 2. The excessive consumption of energy relative to actual requirements… · 3. The government's failure to respond with sufficient speed…
Reading1. Nominalisation enables writers to package complex ideas into dense, information-rich phrases, and it removes the need to specify agents, creating an impersonal, objective tone. · 2. Critics argue that excessive nominalisation can render texts impenetrable, particularly for non-specialist readers.
Unit 02
Global Economics
Exercise 11. It is believed that the policy has failed. · 2. The reform is considered to be inadequate. · 3. It is estimated that inflation will reach 5%. · 4. The CEO is known to have resigned under pressure. · 5. Growth is expected to slow.
Exercise 21. Having been warned about the risks, → the investors nonetheless proceeded with the deal. · 2. It is widely acknowledged that → quantitative easing prevented a deeper recession. · 3. The policy, having been implemented → without adequate consultation, was met with resistance. · 4. It has long been argued that → deregulation benefits large corporations disproportionately. · 5. The data, having been collected → over a five-year period, provides robust evidence.
Reading1. The assumption that financial markets were essentially self-correcting and that the 'invisible hand' would ensure efficient resource allocation without significant government intervention. · 2. Austerity measures are now thought to have prolonged the economic recovery in several European economies.
Unit 03
Scientific Method
Exercise 11. To some extent · 2. There is some evidence to suggest · 3. One might argue · 4. It would appear · 5. arguably
Exercise 21. The drug appears to show promising results in early trials. · 2. One might question whether this theory adequately accounts for all the evidence. · 3. The data suggests a possible correlation, though further research is needed.
Reading1. Because science deals in probabilities rather than certainties, and a single study cannot definitively prove a hypothesis — only provide evidence consistent with it. Hedging reflects this inherent uncertainty. · 2. By presenting claims modestly, researchers invite dialogue rather than confrontation within the academic community.
Unit 04
Philosophy of Mind
Exercise 11. Were · 2. submit · 3. Should · 4. Be · 5. be
Exercise 21. repeat · 2. Were · 3. be
Reading1. Chalmers distinguished between 'easy' problems (mechanisms of perception, memory, attention) and the 'hard' problem (why subjective experience exists at all). This highlighted that explaining brain function does not necessarily explain consciousness itself. · 2. Materialists argue that if dualism were correct, it would be impossible to explain how mental states interact with the physical world — the so-called interaction problem.
Unit 05
Investigative Journalism
Exercise 11. denied leaking / denied having leaked · 2. urged him to consult · 3. acknowledged that mistakes had been made / insisted that they were fixing · 4. warned that the source might not be · 5. maintained that she had not been involved
Exercise 21. deny → + -ing (denied doing) or + that clause · 2. urge → + object + to infinitive (urged them to act) · 3. insist → + that clause (insisted that it was true) · 4. warn → + object + not to / + that clause · 5. concede → + that clause (conceded that errors occurred)
Reading1. The government insisted the disclosures endangered national security, while the whistleblower maintained the public had a right to know about mass surveillance programmes. · 2. Historians acknowledge that the case fundamentally altered the global conversation about digital privacy.
Unit 06
Bioethics
Exercise 11. Had I known · 2. Were she to refuse · 3. Should it emerge · 4. Had the gene therapy been · 5. Were the patient
Exercise 21. Had · 2. Were · 3. Should
Reading1. The passage argues that extending the right to modify genetic material to decisions about future generations raises consent issues, because an unborn child cannot consent to genetic modifications made on their behalf. · 2. By imposing moratoriums on certain forms of research, bioethics committees have prevented experiments from outpacing society's capacity for ethical reflection.
Unit 07
Urban Planning
Exercise 11. Nevertheless · 2. However · 3. Notwithstanding · 4. Consequently · 5. Furthermore
Exercise 21. Furthermore → Addition — adding a supporting point · 2. Nevertheless → Contrast — introducing an opposing point · 3. Consequently → Result — showing a logical outcome · 4. Notwithstanding → Concession — acknowledging despite opposition · 5. In light of → Summary — drawing on preceding evidence
Reading1. Cities must accommodate growing populations while simultaneously reducing their environmental impact. · 2. The passage recommends a balanced approach combining densification with infrastructure investment, affordable housing, and stakeholder consultation, but admits this is easier in theory than in practice.
Unit 08
Artificial Intelligence Ethics
Exercise 11. published · 2. which · 3. whom · 4. processing · 5. introduced
Exercise 21. having · 2. whom · 3. introduced
Reading1. A hiring tool developed by a major tech company was found to penalise candidates from certain demographic groups. The bias was inherited from historical training data reflecting existing societal prejudices. · 2. Because the pace of technological proliferation outstrips regulators' capacity, and many regulators lack the technical expertise to evaluate the AI systems under their purview.
Unit 09
International Law
Exercise 11. incumbent · 2. due · 3. accordance · 4. pursuant to · 5. noted
Exercise 21. start → commence · 2. try → endeavour · 3. help → facilitate · 4. get → obtain · 5. about / to do with → pertaining to / with regard to
Reading1. The international legal order lacks the enforcement capacity of domestic legal systems, meaning compliance is largely voluntary. · 2. Strengthening international institutions without undermining the sovereignty that states regard as fundamental to their identity and legitimacy.
Unit 10
Creative Industries
Exercise 11. What worries me most is · 2. It was only after · 3. Not until the exhibition opened · 4. Never has the industry faced · 5. Only through public investment can we
Exercise 21. What concerns me · 2. No sooner · 3. It was only
Reading1. The creative industries generate more revenue than ever, yet many individual artists struggle to earn a living — despite unprecedented technological empowerment and access to distribution. · 2. Algorithms designed to maximise engagement reward the familiar over the innovative, leading to homogenisation.
Step 2 — Units 11–20
Unit 11
Diplomacy & Conflict
Exercise 11. not · 2. did · 3. so · 4. did · 5. was
Exercise 21. did · 2. so · 3. to
Reading1. It allows each party to interpret a statement in a way that serves its domestic audience, even if the other side interprets it differently, creating space for agreement. · 2. It conveyed both optimism about disarmament and an acknowledgement of division without attributing dissent to any specific party.
Unit 12
Environmental Policy
Exercise 11. is due to be · 2. are to · 3. were about to · 4. are bound to · 5. are to
Exercise 21. be to → formal arrangement, obligation, or condition · 2. be about to → immediate imminence · 3. be due to → expected timing or schedule · 4. be bound to → near-certainty or inevitability · 5. be to (conditional) → 'If we are to succeed' = necessary condition
Reading1. Emissions are to be halved by 2030 to limit warming to 1.5 degrees, but current policies fall far short of achieving this target. · 2. Renewable energy investment is about to surpass fossil fuel investment for the first time, a milestone that arrived sooner than many expected.
Unit 13
Literary Criticism
Exercise 11. alliteration · 2. metaphor · 3. irony · 4. juxtaposition · 5. allegory
Exercise 21. The author employs a sustained water motif throughout the text. · 2. The juxtaposition of 'war' and 'peace' foregrounds the tension between them. · 3. The character's ironic comment underscores their frustration.
Reading1. Defamiliarisation is the concept that literature's purpose is to make the familiar strange. It was coined by the Russian formalist critic Viktor Shklovsky. · 2. In everyday communication, language is transparent — we look through it to the meaning. In literature, foregrounding makes language opaque, inviting us to look at the language itself.
Unit 14
Neuroscience
Exercise 11. did · 2. had · 3. had · 4. is · 5. had
Exercise 21. than · 2. but · 3. when
Reading1. The assumption that the adult brain was fixed — that damaged neurons could not be replaced and lost functions could not be recovered. · 2. The commercial sector marketed 'brain training' applications with claims that far outstripped the scientific evidence, oversimplifying and exploiting the research.
Unit 15
Digital Transformation
Exercise 11. draws · 2. wake · 3. view · 4. poses · 5. grounds
Exercise 21. reach a consensus → agree / come to an agreement · 2. pose a challenge → create a problem / be difficult · 3. address a concern → deal with a worry · 4. draw a conclusion → decide / figure out · 5. undertake a review → look into / check
Reading1. The pandemic compelled organisations that had resisted change to adopt new technologies virtually overnight, accelerating digital transformation at an unexpected pace. · 2. Economists draw a distinction between productive innovation and 'rent-seeking' behaviour — the extraction of value without creating it.
Unit 16
Human Rights
Exercise 11. Granting that · 2. albeit · 3. Much as · 4. For all that · 5. Granting that
Exercise 21. The reform passed, albeit with significant opposition. · 2. Much as I admire her courage, I question her strategy. · 3. He is a flawed leader. For all that, he commands loyalty.
Reading1. The ICC has been criticised for focusing disproportionately on cases from the Global South, though the passage notes there is some justification given the severity of the atrocities investigated. · 2. It grants that cultural differences must be respected, but argues that persecution of individuals on the basis of identity or beliefs cannot be justified on cultural grounds.
Unit 17
Quantum Physics
Exercise 11. had produced · 2. updated · 3. went · 4. had · 5. explained
Exercise 21. were · 2. could have seen · 3. took
Reading1. Einstein objected to the probabilistic nature of quantum mechanics ('God does not play dice'). He did not live to see the experimental confirmation of Bell's theorem, which supported the quantum mechanical predictions he had disputed. · 2. The gap between the extraordinary practical success of quantum mechanics (underpinning technologies like lasers and smartphones) and the public's almost total incomprehension of its basic principles.
Unit 18
Media Ethics
Exercise 11. Don't share stuff you haven't checked. / You shouldn't spread things that haven't been verified. · 2. They did a full investigation. / They looked into it properly. · 3. The editor admitted they'd made mistakes. · 4. There aren't enough ways to hold people accountable. / The accountability systems aren't good enough. · 5. You've got to check your sources. / Sources need to be double-checked.
Exercise 21. The publication subsequently retracted the article. → The paper pulled the story afterwards. · 2. A thorough investigation was conducted. → They looked into it properly. · 3. The journalist's objectivity was called into question. → People questioned whether the journalist was being fair. · 4. It is incumbent upon the editor to verify all claims. → The editor needs to check everything. · 5. The proliferation of clickbait has undermined trust. → All this clickbait has made people stop trusting the news.
Reading1. They were designed for print newspapers and scheduled broadcasts, not for a world where anyone with a smartphone can reach millions instantly. · 2. It contrasts formal analysis ('The proliferation of misinformation poses a threat…') with a media critic's informal podcast quote ('people don't share boring headlines. They share the outrageous stuff, even if it's rubbish').
Unit 19
Cultural Anthropology
Exercise 11. transmission · 2. prohibitions / restrictions · 3. contact / encounters · 4. practices / traditions · 5. bias / tendency
Exercise 21. relationships · 2. Specifically · 3. impact
Reading1. The passage describes culture as a 'living fabric woven from countless threads', emphasising that its elements — language, ritual, kinship, belief, material practice — are interconnected, so that change in one affects the whole. · 2. Through rituals, language, and the transmission of oral histories — practices that serve as active resistance against assimilation rather than mere nostalgia.
Unit 20
Future of Humanity
Exercise 11. It is thought that AI poses risks. / AI is thought to pose risks. · 2. Were the government not to invest now, the opportunity would be lost. · 3. Much as the technology is impressive, it raises ethical questions. · 4. It's high time people started taking this seriously. · 5. What the rapid development of AI has created is a set of new challenges.
Exercise 21. Never before has such a challenge been faced. · 2. Had we prepared for this scenario, the outcome might have been different. · 3. The trend is expected to continue.
Reading1. The passage argues the central concern is not technology itself but the structures of governance within which it operates — or the lack thereof. · 2. Intergenerational equity — because today's decisions shape the world inherited by future generations who had no voice in making those decisions.