영어 모의고사 (자동 편성)

Exercise does far more than strengthen muscles and the heart; it also produces measurable changes within the brain itself. During sustained physical activity, the body ①releases a protein called brain-derived neurotrophic factor, which supports the growth of new neurons and ②strengthens connections between existing ones, particularly in regions associated with memory and learning. Studies comparing physically active students to sedentary peers have repeatedly found that the active group ③performing better on tests of attention and problem-solving, even when the exercise session ends well before the test begins. Researchers believe that exercise increases blood flow to the brain, ④delivering oxygen and nutrients more efficiently, while also reducing levels of stress hormones that can interfere with clear thinking. These findings have encouraged some schools ⑤to schedule exercise before demanding academic classes.

Climate scientists frequently warn about tipping points, thresholds beyond which a small additional change ①triggers a large, often irreversible shift in the climate system. Unlike gradual warming, which unfolds steadily over decades, crossing a tipping point can produce dramatic consequences within a short period. For instance, as Arctic ice melts, it exposes darker ocean water that ②absorb more sunlight than reflective ice, accelerating further melting in a self-reinforcing cycle. Similarly, scientists worry that a major ocean current, which currently ③redistributes heat across the planet, could slow dramatically if enough freshwater from melting glaciers dilutes the surrounding seawater. Once such thresholds are crossed, ④restoring the original balance may become nearly impossible, even if emissions are later reduced. Therefore, researchers argue that preventing these transitions ⑤matters more than merely slowing average temperature increases.

Smartphones, tablets, and computer screens all emit a significant amount of blue light, a short-wavelength light that our eyes are especially ①sensitive to. During the day, exposure to blue light from the sun helps keep us alert and mentally sharp, which is generally beneficial. At night, however, the same wavelength can interfere with the body's natural preparation for sleep. Specialized cells in the retina ②detect blue light and send signals to the brain's internal clock, ③suppressing the release of melatonin, the hormone that signals it is time to rest. Studies have found that ④people who scroll through their phones in bed before sleeping take longer to fall asleep and experience lighter, more easily disrupted sleep than those who avoid screens. Some devices now offer a night mode that shifts the display toward warmer tones, reducing blue light output in the evening. While this feature may help slightly, sleep researchers generally recommend ⑤limit screen use altogether in the hour before bedtime for the best results.

When people discuss climate change, they often focus only on rising temperatures or melting ice, ①treating it as a purely scientific issue. However, the concept of climate justice reminds us that the causes and consequences of climate change are ②distributed unevenly across the globe. Wealthy, industrialized nations have historically released the largest share of greenhouse gases while building their economies, yet developing nations, ③which contributed comparatively little, frequently suffer the most severe droughts and floods. This gap between responsibility and suffering ④raises a serious ethical question that science alone cannot answer. For example, a farming community in a low-income country may lose its entire harvest to an unusual flood, even though its members have never owned a car or ⑤flying on a plane. Therefore, tackling climate change requires more than new technology; it demands fair policies supporting the very communities least responsible for causing the crisis.

Smart speakers have quietly become a fixture in many households, responding to spoken requests for weather updates, music, or kitchen timers. Behind this ①simple exchange lies a complex process: the device converts sound waves into text, interprets the meaning using language models, and then generates a spoken reply, all within a second or two. Because these assistants ②improve by learning from millions of interactions, they gradually become better at recognizing regional accents and casual phrasing that once confused them. Still, the technology remains far from ③perfect. Background noise, overlapping voices, or an unusual sentence structure can cause the assistant to misunderstand a simple request, sometimes with ④flawless results. Engineers continue to refine these systems, but many admit that truly natural conversation remains one of the hardest ⑤goals in the entire field of artificial intelligence.

To compensate for their carbon emissions, many individuals and companies now purchase carbon offsets, financial credits that fund projects such as planting trees or building renewable energy plants. The idea is appealing: paying for an equivalent amount of carbon to be absorbed elsewhere should cancel out the harm caused by activities like flying. However, critics argue that this system often functions as _______________. For example, a newly planted forest may take decades to absorb the promised carbon, and it could later burn down or be cut, erasing any benefit. Moreover, some offset projects would have happened anyway, meaning the credits fund nothing truly additional. Therefore, relying heavily on offsets allows businesses to maintain harmful practices while appearing responsible. Experts insist that offsetting should complement, not replace, direct reductions in fossil fuel use if the strategy is to remain credible.

For decades, athletes were taught to stretch a muscle and hold the position before any competition, believing that this practice alone would prevent injury. Recent research, however, has complicated that assumption considerably, since static stretching, in which a muscle is held at its longest length for an extended period, can actually _______________. Dynamic stretching, which involves controlled, repeated movement through a joint's full range of motion, appears to prepare muscles for activity without this problem.

Many people who try digital detox for the first time report feeling anxious within the first few hours. (A) This initial discomfort, sometimes called withdrawal anxiety, tends to fade after a day or two as the mind adjusts to reduced stimulation. (B) Once that adjustment period passes, most participants describe a noticeable sense of calm that they had not expected. (C) This unexpected calm often motivates people to repeat the practice regularly instead of treating it as a one-time experiment.

When the body fights off an infection, the immune system relies heavily on adequate sleep to function effectively. (A) Rather than being a passive state in which the body simply rests, sleep functions as an active period during which the immune system repairs itself and prepares for future threats, which is why doctors often recommend extra sleep when someone is fighting an illness. (B) Chronic sleep deprivation also appears to promote low-grade inflammation throughout the body, a state that has been linked to a higher risk of heart disease and other chronic conditions. (C) During deep sleep, the body produces and releases cytokines, proteins that help regulate immune responses, and people who consistently sleep fewer than six hours a night show measurably weaker antibody responses after vaccination.

Mira grew up in a small village where fishing and farming had sustained her family for generations. (A) International organizations, however, still struggle to agree on how to protect people like her, since climate migrants are not officially recognized as refugees under current law. (B) Mira missed her old house terribly, yet she slowly began to build a new life in the crowded city, learning to adapt just as her ancestors once had. (C) When the sea finally swallowed the rice paddies that had fed her village for generations, her parents decided that staying was no longer possible. Together with many neighbors, they packed what little they could carry and moved inland, becoming what experts now call climate migrants, people forced to abandon their homes because of rising seas, droughts, or other disasters. This term, rarely used a decade ago, has become increasingly common as extreme weather displaces communities worldwide.