Đề thi thử số 5 — Reading 40 câu (có bài đọc)

Water is one of the most essential resources on Earth, yet its availability is increasingly threatened by a combination of population growth, urbanization, agricultural demand, and climate change. Although approximately 71 percent of the Earth's surface is covered by water, only about 2.5 percent of that water is fresh, and less than one percent is readily accessible for human use. As global demand for clean water continues to rise, the need for effective water conservation strategies has become more urgent than ever before.

Agriculture is by far the largest consumer of freshwater resources, accounting for approximately 70 percent of global water withdrawals. Irrigation systems used in farming often waste significant amounts of water through evaporation, runoff, and inefficient distribution methods. Modern technologies such as drip irrigation, which delivers water directly to plant roots through a network of tubes and emitters, can reduce agricultural water use by up to 60 percent compared to traditional flood irrigation methods. Despite these advances, adoption of water-efficient technologies remains limited in many developing countries due to high initial costs and lack of technical knowledge among farmers.

Household water conservation plays an important role in reducing overall water consumption, particularly in urban areas where population density places heavy demands on municipal water supplies. Simple behavioral changes, such as fixing leaky faucets, taking shorter showers, and using water-efficient appliances, can significantly reduce household water use. Studies have shown that a single dripping faucet can waste up to 20,000 liters of water per year, while water-efficient showerheads and toilets can reduce household consumption by 30 to 40 percent. Public awareness campaigns and water pricing policies that reflect the true cost of water treatment and distribution have proven effective in encouraging conservation behavior among urban residents.

Rainwater harvesting represents an ancient yet increasingly relevant approach to water conservation. By collecting and storing rainfall from rooftops and other surfaces, households, farms, and communities can supplement their water supply without drawing from rivers, lakes, or underground aquifers. In many parts of India, Africa, and Southeast Asia, traditional rainwater collection systems have been practiced for centuries and are now being revived and modernized with improved storage tanks and filtration systems. Singapore, despite being one of the most water-scarce nations in the world, has invested heavily in rainwater harvesting infrastructure, collecting approximately two-thirds of the island's rainfall for treatment and reuse.

Desalination, the process of removing salt from seawater to produce freshwater, offers another potential solution to water scarcity, particularly for coastal regions and island nations. Technological advances have significantly reduced the energy consumption and cost of desalination in recent decades, making it an increasingly viable option. Countries such as Saudi Arabia, Israel, and Australia now rely on desalination for a substantial portion of their freshwater supply. However, desalination remains energy-intensive and generates brine waste that can harm marine ecosystems if not properly managed. Experts agree that a comprehensive approach to water conservation — combining efficient use, recycling, rainwater harvesting, and where necessary, desalination — is essential for ensuring sustainable water supplies in an increasingly water-stressed world.

The gig economy, a labor market characterized by short-term contracts and freelance work rather than permanent employment, has expanded rapidly over the past decade, fueled by digital platforms that connect workers with customers for specific tasks or services. Companies such as Uber, Grab, Airbnb, and Fiverr have become household names, offering millions of people around the world opportunities to earn income on their own terms. While the gig economy provides undeniable flexibility and accessibility, it has also sparked intense debate about workers' rights, economic security, and the future of employment.

Flexibility is widely regarded as the gig economy's most attractive feature. Gig workers can choose when, where, and how much they work, allowing them to balance earning income with other responsibilities such as childcare, education, or pursuing creative interests. For many people, particularly those who face barriers to traditional employment due to disabilities, caregiving obligations, or geographic isolation, the gig economy offers a lifeline of economic participation that would otherwise be unavailable. A survey conducted by McKinsey Global Institute found that approximately 30 percent of gig workers in the United States and Europe chose independent work as their primary income source by preference rather than necessity, valuing the autonomy it provides.

However, the benefits of flexibility come at a significant cost for many gig workers. Unlike traditional employees, most gig workers are classified as independent contractors, which means they are typically not entitled to benefits such as health insurance, paid sick leave, retirement contributions, or unemployment protection. This classification also means that gig workers bear the full burden of taxes, equipment costs, and business expenses that would normally be shared with an employer. During the COVID-19 pandemic, the vulnerability of gig workers became starkly apparent, as millions of drivers, delivery couriers, and freelancers lost their income overnight with no safety net to fall back on.

The question of how to classify and regulate gig workers has become one of the most contentious labor issues of the twenty-first century. In 2020, California passed Assembly Bill 5, which established stricter criteria for classifying workers as independent contractors and required many gig companies to reclassify their workers as employees entitled to standard benefits. The legislation faced fierce opposition from platform companies, which argued that reclassification would undermine their business models and reduce opportunities for workers who value flexibility. A subsequent ballot measure, Proposition 22, partially reversed the law by creating a third category of worker with some but not all employee benefits, illustrating the difficulty of finding regulatory solutions that satisfy all stakeholders.

The gig economy's long-term trajectory will depend on how societies choose to balance innovation with worker protection. Some economists argue that the traditional employment model, with its bundled package of wages, benefits, and job security, is an artifact of the twentieth century that may not suit the realities of a rapidly changing digital economy. Others contend that allowing companies to shift the costs and risks of employment onto individual workers represents a regression to the exploitative labor practices of the pre-industrial era. Emerging models that provide portable benefits tied to individual workers rather than specific employers, and that establish minimum earnings guarantees for platform workers, offer promising middle-ground approaches. Whatever direction policy takes, the gig economy has permanently altered the landscape of work, forcing societies to reconsider fundamental assumptions about what it means to be employed in the modern world.

Biodiversity, the variety of life on Earth encompassing all species of plants, animals, fungi, and microorganisms as well as the ecosystems they inhabit, is declining at a rate unprecedented in human history. The Living Planet Report published by the World Wildlife Fund documents an average 69 percent decline in monitored wildlife populations between 1970 and 2018, a statistic that has alarmed scientists and policymakers worldwide. This mass extinction event, sometimes termed the sixth extinction, is driven almost entirely by human activities and carries consequences that extend far beyond the aesthetic loss of charismatic species to threaten the ecological systems upon which human civilization depends.

Habitat destruction represents the single greatest driver of biodiversity loss globally. The conversion of forests, wetlands, grasslands, and coastal areas into agricultural land, urban developments, and industrial zones has eliminated or degraded the natural habitats upon which countless species depend for survival. Tropical deforestation is particularly devastating, as tropical forests harbor an estimated 50 to 80 percent of all terrestrial species despite covering only about 6 percent of the Earth's land surface. Between 2001 and 2020, the world lost approximately 411 million hectares of tree cover, an area roughly the size of the European Union. The fragmentation of remaining habitats into isolated patches further exacerbates the problem, as small, disconnected populations become more vulnerable to genetic deterioration, disease, and local extinction.

The economic and practical consequences of biodiversity loss are substantial and underappreciated. Ecosystem services — the benefits that natural systems provide to human societies — include pollination of food crops, purification of air and water, regulation of climate, decomposition of waste, and provision of raw materials for medicine and industry. The economic value of these services has been estimated at trillions of dollars annually, far exceeding the global GDP. Approximately 75 percent of the world's food crops depend to some degree on animal pollinators, predominantly bees, whose populations have declined dramatically in recent decades due to pesticide exposure, habitat loss, and disease. The collapse of pollinator populations would have catastrophic implications for global food security, affecting the availability and price of fruits, vegetables, nuts, and seeds worldwide.

Climate change and biodiversity loss are deeply interconnected, operating as mutually reinforcing crises that amplify each other's severity. Rising temperatures, altered precipitation patterns, and increased frequency of extreme weather events force species to migrate, adapt, or face extinction. Coral reefs, among the most biodiverse ecosystems on Earth, have experienced mass bleaching events with increasing frequency, threatening the livelihoods of half a billion people who depend on reef fisheries and tourism. Conversely, the loss of biodiversity undermines the capacity of ecosystems to absorb and store carbon dioxide, reducing nature's ability to mitigate climate change. Deforestation alone contributes approximately 10 percent of global greenhouse gas emissions, creating a destructive feedback loop in which biodiversity loss accelerates climate change, which in turn drives further biodiversity loss.

Reversing the trend of biodiversity decline requires transformative changes across economic, political, and social systems. The Kunming-Montreal Global Biodiversity Framework, adopted in 2022, establishes the ambitious target of protecting 30 percent of the world's land and ocean areas by 2030, a commitment known as "30 by 30." Achieving this target will require not only the expansion of protected areas but also fundamental reforms to agricultural subsidies, trade policies, and consumption patterns that currently incentivize the destruction of natural habitats. Indigenous and local communities, whose traditional land management practices have sustained biodiversity for millennia, must be recognized as essential partners in conservation efforts rather than marginalized by top-down approaches. The scientific consensus is clear: preserving biodiversity is not merely an environmental luxury but an existential necessity for maintaining the ecological foundations of human well-being and economic prosperity.

The concept of smart cities has evolved from a futuristic vision into a tangible reality as urban centers worldwide increasingly deploy interconnected digital technologies to enhance the quality of life for their residents, improve the efficiency of public services, and address the complex challenges of rapid urbanization. A smart city integrates information and communication technology with Internet of Things devices, data analytics, and artificial intelligence to create an urban environment that is responsive, adaptive, and sustainable. While the term encompasses a broad spectrum of initiatives, the underlying premise is consistent: leveraging technology and data to make urban governance more informed, infrastructure more efficient, and citizen engagement more meaningful.

Transportation represents one of the most visible and impactful domains of smart city implementation. Intelligent traffic management systems use real-time data from sensors, cameras, and connected vehicles to dynamically adjust traffic signal timing, reducing congestion and commute times by up to 25 percent in some cities. Public transit agencies are deploying GPS-enabled tracking systems that provide passengers with accurate arrival predictions through smartphone applications, while ride-sharing platforms and autonomous vehicle trials are reshaping urban mobility patterns. Barcelona, widely regarded as one of the world's leading smart cities, has implemented an integrated mobility platform that coordinates buses, metro lines, bicycle-sharing programs, and electric scooter networks into a seamless multimodal transportation system accessible through a single application.

Energy management is another critical area where smart city technologies are delivering measurable benefits. Smart grids equipped with advanced metering infrastructure enable utility companies to monitor electricity consumption in real time, detect outages rapidly, and optimize distribution to reduce waste. Smart buildings equipped with automated lighting, heating, and cooling systems can reduce energy consumption by 20 to 30 percent compared to conventional buildings. In Songdo, South Korea, a purpose-built smart city, a centralized pneumatic waste collection system eliminates the need for garbage trucks by transporting waste through underground pipes directly to processing facilities, reducing both traffic congestion and air pollution associated with traditional waste collection.

The proliferation of data collection inherent in smart city infrastructure raises profound questions about privacy, surveillance, and the relationship between citizens and the state. The dense networks of sensors, cameras, and connected devices that enable smart city functionality also create unprecedented capacity for monitoring the movements, behaviors, and activities of urban residents. Critics argue that without robust data protection frameworks and transparent governance structures, smart city technologies risk creating digital panopticons in which citizens are subject to constant surveillance by both government agencies and private corporations. The experience of Sidewalk Labs' abandoned smart city project in Toronto, which was terminated in 2020 amid public backlash over data governance concerns, illustrates the potential for citizen resistance when smart city initiatives are perceived as prioritizing technological ambition over democratic accountability.

The equitable distribution of smart city benefits presents an additional challenge that technologists and policymakers must confront. There is a substantial risk that smart city technologies will disproportionately benefit affluent neighborhoods and digitally connected populations while leaving underserved communities further behind. Residents who lack smartphones, internet access, or digital literacy skills may be unable to access smart services, effectively creating a two-tiered urban experience that deepens existing social and economic inequalities. Ensuring that smart city development is inclusive and participatory — engaging diverse communities in the design and implementation process — is essential for preventing the emergence of what scholars have termed "smart divides" that replicate and amplify the digital divides already present in contemporary societies. The ultimate measure of a smart city's success should not be the sophistication of its technology but the extent to which it improves the lives of all its residents, including its most vulnerable members.