영어 모의고사 (자동 편성)

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. 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 ①waking up fully. Because these interruptions rarely produce a clear memory the next morning, many people remain ②unaware that anything is wrong, even as chronic fatigue, headaches, and irritability build up over months. 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 ③recording in a sleep laboratory. ④Left 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 ⑤suggest.

Skipping a proper warm-up before intense exercise might seem like a harmless way to save a few minutes, but the practice ①carries real physiological costs. A cold muscle is stiffer and less elastic than a warm one, making it considerably more prone to strains and tears when suddenly ②asked to contract forcefully. Gradually raising body temperature through light activity increases blood flow to the muscles, ③allowing oxygen to reach tissue more efficiently and enabling nerve signals to travel faster between the brain and the muscle fibers. A proper warm-up also raises heart rate gradually, ④easing the cardiovascular system into strenuous work rather than shocking it with a sudden demand. Athletes who warm up thoroughly tend to report better performance in the early minutes of competition, since their bodies are already primed rather than ⑤adjust on the fly.

A navigation app calculating a route rarely relies on distance alone; instead, it constantly weighs real-time traffic reports, past congestion patterns for that time of day, and even data from other drivers' phones currently on the road. This flood of information allows the app to ①reroute a driver away from a sudden accident within seconds, often before the driver has any idea the accident occurred at all. The convenience comes at a ②cost that few passengers consider, however. When thousands of drivers are simultaneously redirected onto the same shortcut, that quiet side street can quickly become as ③congested as the highway it was meant to help travelers avoid. Residents of these once-quiet neighborhoods have increasingly ④complained about the sudden surge of unfamiliar traffic, arguing that an algorithm optimizing for individual convenience can end up ⑤solving a new, entirely different problem for the wider community.

A short nap taken in the early afternoon, often called a power nap, can noticeably sharpen attention and mood without leaving a person ①refreshed afterward. The key lies in timing: naps limited to roughly twenty minutes allow the brain to pass through the ②lightest stages of sleep while avoiding the deeper stages associated with slow-wave activity. If a nap extends much beyond that window, the sleeper risks waking during deep sleep, which produces a ③foggy, disoriented feeling known as sleep inertia that can persist for thirty minutes or more. Laboratory studies comparing napping and non-napping groups have ④repeatedly shown that a brief nap improves reaction time and short-term memory almost as effectively as a full night of extra rest. Interestingly, the benefit appears ⑤strongest when the nap occurs several hours after waking, since this is when the body's natural dip in alertness makes rest most effective.

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 higher than those of untrained individuals. While genetics accounts for a substantial portion of an individual's potential VO2 max, consistent aerobic training can still raise the measurement considerably over months of dedicated effort. It is worth noting, however, that a high VO2 max does not guarantee success in competition, since _______________.

Modern sports wearables continuously collect data that would once have required a laboratory to measure, allowing coaches to detect early warning signs of overtraining, sometimes noticing a decline in performance before the athlete consciously feels tired. However, the flood of data has created a new challenge: _______________. Some researchers worry that casual users may misinterpret a single unusual reading as a serious problem, leading to needless anxiety rather than useful insight.

Every cell in the human body follows an internal timer known as the circadian rhythm, a roughly twenty-four-hour cycle that governs when we feel alert and when we feel drowsy. This clock is regulated primarily by a tiny cluster of neurons in the brain that responds to light entering through the eyes. When morning sunlight strikes the retina, the cluster signals the body to suppress sleep hormones and raise body temperature, preparing us for activity. As evening approaches and light fades, _______________. Because this rhythm evolved around the natural cycle of day and night, modern habits such as staying indoors under artificial light or working night shifts can push the internal clock out of sync with the external environment. Such misalignment does not simply cause tiredness; it has also been associated with digestive problems and reduced concentration, suggesting that timing matters as much as total sleep hours.

Scientists have identified certain gene variants that appear more frequently among elite endurance athletes than among the general population, along with a separate set that seems to favor explosive, power-based sports such as sprinting. One frequently studied variant, for instance, influences the proportion of slow-twitch versus fast-twitch muscle fibers a person naturally develops, a ratio that shapes whether a body leans toward endurance or explosive power. However, researchers caution strongly against interpreting these findings as evidence that athletic greatness is simply inherited, since _______________. Genetics may set a rough ceiling on an individual's ultimate potential, but where any particular athlete lands within that range depends overwhelmingly on training quality, nutrition, coaching, and sheer determination.

This happens because the eyes remain remarkably responsive to light even after darkness falls, cueing the brain that it is still daytime. Smartphones, tablets, and computer screens all emit a significant amount of blue light, a short-wavelength light that our eyes are especially sensitive to. ( ① ) During the day, exposure to blue light from the sun helps keep us alert and mentally sharp, which is generally beneficial. ( ② ) At night, however, the same wavelength can interfere with the body's natural preparation for sleep. ( ③ ) Specialized cells in the retina detect blue light and send signals to the brain's internal clock, suppressing the release of melatonin, the hormone that signals it is time to rest. ( ④ ) Studies have found that people 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. ( ⑤ ) 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 limiting screen use altogether in the hour before bedtime for the best results.

The psychological weight of that pressure can undermine skills that otherwise feel completely automatic in practice. Elite athletes often perform in front of enormous crowds with championships, contracts, and years of training riding on a single moment. ( ① ) Sports psychologists explain that intense anxiety narrows attention and disrupts the smooth, unconscious execution of well-learned movements, a phenomenon sometimes called choking under pressure. ( ② ) Rather than trying to eliminate nervousness entirely, which research suggests is nearly impossible, many trainers now teach athletes to reinterpret the physical symptoms of anxiety, such as a racing heart, as signs of readiness rather than danger. ( ③ ) Structured breathing exercises and pre-performance routines also help athletes regain a sense of control before a decisive moment. ( ④ ) Over time, repeated exposure to high-pressure situations in practice, deliberately simulated to resemble real competition, allows athletes to build tolerance the same way their muscles adapt to physical training. ( ⑤ )