영어 모의고사 (자동 편성)

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.

Sleep debt refers to the ①cumulative gap between the amount of sleep a person needs and the amount they actually get. Unlike a financial debt, however, this deficit cannot simply be ②repaid with a single long weekend of rest. When someone loses two hours of sleep every night for a week, the body does not treat the shortage as fourteen separate small losses; instead, it ③accumulates the deficit, and the resulting impairment in attention and mood can resemble that of a person who has been awake for an entire night. Researchers have found that even modest, chronic sleep restriction gradually impairs reaction time and decision-making, often without the affected person noticing the decline. This is because subjective feelings of tiredness tend to plateau after a few days, even as objective performance keeps deteriorating. Consequently, people frequently ④underestimate how much sleep debt they are carrying until a demanding task suddenly exposes the ⑤diminished cost.

In the days leading up to an endurance event, many athletes deliberately increase their carbohydrate intake while reducing training volume, a practice known as carbohydrate loading. The strategy is designed to maximize the amount of glycogen, the storage form of carbohydrate, packed into muscle tissue before competition begins. Because glycogen serves as the primary fuel source during prolonged, intense exercise, _______________. Sports nutritionists caution, however, that the timing and composition of meals matter as much as the total quantity of carbohydrate consumed, since eating unfamiliar foods immediately before competition can cause digestive discomfort.

When people encounter solid scientific evidence about climate change, we might expect them to accept it without hesitation. However, many individuals still dismiss or downplay such evidence, and psychologists explain this pattern through a concept called motivated reasoning. Motivated reasoning refers to _______________. For example, a person whose livelihood depends on the fossil fuel industry may unconsciously search for reasons to doubt climate data, even while claiming to value scientific accuracy. This happens because accepting uncomfortable facts can threaten a person's sense of self or demand costly lifestyle changes. Therefore, simply presenting more data rarely persuades a committed skeptic. Instead, experts suggest connecting climate information to values the person already holds, such as family safety or economic stability, so that acceptance feels natural rather than threatening.

Behavioral economists use the term status quo bias to describe a tendency to prefer the present situation over a new alternative, even when the alternative would bring greater benefits. This bias helps explain why many households hesitate to switch to renewable energy, such as installing solar panels on their roofs. Although solar panels can lower electricity bills over time, homeowners often stick with their current power source because it feels safe and requires no immediate effort. In contrast, switching demands research, upfront cost, and trust in unfamiliar technology, all of which can seem risky compared with doing nothing. For example, a neighborhood association might repeatedly postpone a vote on shared solar panels, not because the plan is flawed, but because members are reluctant to leave their routine. Therefore, boosting renewable adoption may depend less on proving its advantages and more on _______________.

Caffeine is the most widely consumed stimulant in the world, prized for its ability to sharpen focus and fight off fatigue within minutes of consumption. (A) For this reason, many sleep specialists advise avoiding caffeine after early afternoon, since it can quietly reduce the amount of deep, restorative sleep obtained later at night. (B) It works by blocking adenosine, a chemical that gradually builds up in the brain and makes us feel increasingly sleepy the longer we stay awake. (C) The effects, however, last far longer than most people realize, since caffeine can remain active in the bloodstream for five or six hours after it is consumed.

None of these explanations, in other words, has to be the whole story. For centuries, dreams have fascinated scientists and philosophers alike, yet no single theory fully explains why the sleeping brain generates such vivid and often bizarre experiences. ( ① ) One prominent idea suggests that dreaming helps the brain process emotional experiences, replaying difficult events in a safe, low-stakes environment so that their emotional intensity gradually fades. ( ② ) Another theory proposes that dreams serve a more practical function, allowing the brain to rehearse responses to threats without any real danger, a kind of nightly simulation that may have offered early humans a survival advantage. ( ③ ) Still other researchers argue that dreaming is simply a byproduct of the brain organizing memories, with vivid imagery arising as the mind sorts through the day's information rather than serving any independent purpose of its own. ( ④ ) Because these theories rest on indirect evidence rather than direct observation of subjective experience, none has been conclusively proven. ( ⑤ ) Many scientists now suspect that dreaming may serve several of these functions simultaneously rather than just one.

Whenever a user marks a message as spam or rescues a message mistakenly filtered out, that action becomes new training data, sharpening the filter's future decisions. Every day, email providers quietly block billions of unwanted messages before they ever reach a user's inbox, a task that would be impossible without an AI filtering system running constantly in the background. ( ① ) The filter examines each incoming message for suspicious patterns, including certain keywords, unusual sender addresses, and formatting tricks that scammers commonly rely on to slip past detection. ( ② ) What makes the system effective is that it keeps learning after launch. ( ③ ) This creates a constant back-and-forth, since spammers study which messages get blocked and then adjust their wording to slip through again. ( ④ ) As a result, spam filtering is less like a fixed wall and more like an ongoing contest, with each side continuously adapting to outsmart the other. ( ⑤ )

This shift in emphasis reflects a growing understanding of what actually happens inside the body while an athlete is asleep. Coaches have traditionally focused athlete preparation on training volume and nutrition, but a growing body of research suggests that sleep deserves equal attention. ( ① ) During deep sleep, the body releases growth hormone, a substance essential for repairing muscle tissue damaged during intense training, while the brain consolidates motor skills practiced earlier that day into more stable, efficient patterns. ( ② ) Athletes who sleep fewer than seven hours a night have been shown to suffer more injuries, slower reaction times, and reduced accuracy compared to well-rested peers performing the identical drills. ( ③ ) Frequent travel across time zones compounds this challenge considerably, since jet lag can disrupt an athlete's natural sleep-wake cycle for several days after a long flight, sometimes right before an important competition. ( ④ ) In response, many professional teams now employ sleep specialists who design travel schedules, control bedroom lighting and temperature, and even adjust competition start times when possible. ( ⑤ )

In other words, the two stages appear to serve complementary purposes, one restoring the body and the other restoring the mind. Sleep is not a single, uniform state but a cycle that alternates between two very different modes: REM (rapid eye movement) sleep and non-REM sleep. ( ① ) During non-REM sleep, especially its deepest stage, the brain waves slow down dramatically, the body temperature drops, and tissue repair and growth hormone release reach their peak. ( ② ) This is the period most closely associated with physical restoration. ( ③ ) REM sleep, by contrast, brings rapid eye movements, near-total muscle paralysis, and brain activity that closely resembles wakefulness. ( ④ ) Most vivid dreaming occurs during this stage, and researchers believe it plays a central role in consolidating memories and processing emotional experiences. ( ⑤ ) A healthy night typically cycles through both stages four or five times, with non-REM dominating the early hours and REM periods lengthening toward morning. Disrupting either stage, through frequent awakenings or alcohol use, can leave a person feeling unrested even after a full night in bed.