영어 모의고사 (자동 편성)

Smart speakers have quietly become a fixture in many households, ①responding to spoken requests for weather updates, music, or kitchen timers. Behind this simple 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 improve by ②learning 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 perfect. Background noise, overlapping voices, or an unusual sentence structure can cause the assistant ③misunderstanding a simple request, sometimes with amusing results. Engineers continue to refine these systems, but many admit that truly natural conversation, the kind ④that flows without repeated commands or awkward pauses, ⑤remains one of the hardest goals in the entire field of artificial intelligence.

Anyone who has ridden a bicycle after a decade away from one has likely ①experiencing muscle memory firsthand: the body seems to recall a complex skill almost instantly, even when conscious memory of the exact movements has faded. Contrary to what the name suggests, muscles themselves do not actually store memories; the phenomenon originates in the brain and nervous system, where repeated practice gradually ②shifts control of a well-learned movement from regions associated with conscious thought to areas that operate largely automatically. This shift explains why a skilled athlete can ③execute a complicated sequence of movements without consciously thinking through each individual step, freeing mental attention for strategy and decision-making instead. Interestingly, research also suggests that these neural pathways can remain partially intact even after long periods without practice, which is why relearning a skill is typically much ④faster than learning it for the very first time. Coaches often exploit this principle by ⑤ensuring that fundamental techniques are practiced correctly from the very beginning.

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.

VO2 max, defined as the maximum volume of oxygen a person's body can consume and use during intense exercise, is widely regarded as one of the best single indicators of cardiorespiratory fitness. Elite endurance athletes typically post VO2 max values far ①higher than those of untrained individuals, reflecting hearts that pump larger volumes of blood and muscles that extract oxygen from that blood with remarkable efficiency. While genetics accounts for a substantial portion of an individual's potential VO2 max, consistent aerobic training can still ②raise the measurement considerably over months of dedicated effort. Interval training, which alternates short bursts of near-maximal effort with periods of recovery, has proven particularly ③effective at improving this measurement compared to steady, moderate-intensity exercise alone. It is worth noting, however, that a high VO2 max does not guarantee success in competition, since factors such as running economy, pacing strategy, and mental resilience also play a ④decisive role in determining who actually crosses the finish line first. These additional factors remain ⑤irrelevant to overall performance.

Across the world, teenagers are chronically short on sleep, often getting two or three hours less than the eight to ten hours experts recommend for their age. Part of the problem lies in biology: as puberty begins, the body's internal clock naturally ①shifts later, making it difficult for teenagers to fall asleep before eleven at night. Yet school start times rarely adjust to this shift, forcing students to wake before their bodies are ready. The consequences extend well beyond simple tiredness. Chronic sleep loss during adolescence has been linked to ②impaired concentration, weakened memory, and a higher risk of anxiety and depression. It can also disrupt the hormones that regulate appetite, contributing to ③unhealthy weight gain over time. Some school districts have experimented with delaying start times by even thirty minutes, and early results suggest that students who gain that extra rest show ④worsened grades, better mood, and fewer tardy arrivals. Despite this evidence, changing entrenched school schedules remains a slow and ⑤contentious process.

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.

Coaches have traditionally focused athlete preparation on training volume and nutrition, but a growing body of research suggests that sleep deserves equal attention. 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. As a result, _______________. 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.

Athletes preparing for major endurance events sometimes train for weeks at high altitude, where the air contains less oxygen than at sea level, in hopes of gaining a physiological edge once they return to compete at lower elevations. (A) Many elite programs therefore follow a strategy known as live high, train low, balancing the benefits of altitude exposure against the need for high-quality workouts. (B) In this thin air, the body responds by producing more red blood cells, which carry oxygen more efficiently through the bloodstream to working muscles. (C) However, the benefits of altitude training are far from guaranteed, since individual athletes respond quite differently to the same conditions, and some experience excessive fatigue that undermines the very training they hoped to complete.

During sleep, the brain does not simply rest; it actively reorganizes the day's experiences into lasting memories through a process called consolidation. (A) Sleep researchers have demonstrated this effect experimentally: participants who slept after learning a list of word pairs recalled more items the next day than participants who remained awake instead. Crucially, the benefit was not limited to simple recall; sleep also seemed to help participants extract general patterns from the material, suggesting that consolidation involves more than passive storage. (B) Newly formed memories are initially fragile and stored primarily in a brain region called the hippocampus, which has limited long-term capacity. (C) While a person sleeps, particularly during the deep stages of non-REM sleep, neural activity replays these fresh memory traces in rapid, compressed sequences, gradually transferring the information to the cortex for more durable, long-term storage. This replay strengthens the connections between neurons that encoded the original experience, making the memory more resistant to interference from unrelated events the following day.

Because the airway narrows gradually rather than closing all at once, the severity of each episode can vary widely. Sleep apnea is a disorder in which breathing repeatedly stops and restarts during sleep, often because the muscles at the back of the throat relax too much and block the airway. ( ① ) Each pause can last from a few seconds to over a minute, and it may occur dozens of times in a single night without the sleeper ever waking up fully. ( ② ) Because these interruptions rarely produce a clear memory the next morning, many people remain unaware that anything is wrong, even as chronic fatigue, headaches, and irritability build up over months. ( ③ ) Doctors therefore rely less on a patient's own account of the night and more on objective measurements, such as overnight oxygen levels and airflow patterns recorded in a sleep laboratory. ( ④ ) Left untreated, the disorder has been linked to serious long-term risks, including high blood pressure and heart disease, which makes an accurate diagnosis far more urgent than its subtle nighttime symptoms might suggest. ( ⑤ )