영어 모의고사 (자동 편성)

Athletes preparing for major endurance events sometimes ①trains 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. In this thin air, the body responds by producing more red blood cells, ②which carry oxygen more efficiently through the bloodstream to working muscles. When these athletes return to sea level, where oxygen is more abundant, their blood ③retains this elevated capacity for a limited period, potentially translating into improved endurance performance. 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 ④undermines the very training they hoped to complete. Many elite programs therefore follow a strategy known as live high, train low, in which athletes sleep at altitude to stimulate blood adaptations but perform intense workouts at lower elevation ⑤to maintain quality and intensity.

A smartwatch strapped to a runner's wrist can now do far more than simply count steps; it monitors heart rate variability, running form, and recovery time, then uses that data to suggest a training plan ①tailored to the individual rather than a generic weekly schedule. When the device detects signs of overtraining, such as an unusually high resting heart rate several mornings in a row, it may recommend a ②lighter workout or an extra rest day before fatigue turns into an actual injury. Amateur athletes often credit this kind of guidance with helping them train more ③consistently without pushing their bodies too hard. Sports scientists note an important caveat, however: a wrist-based sensor cannot fully capture the same physiological detail available in a professional lab, so its suggestions should be treated as an ④infallible medical judgment rather than a helpful guideline, particularly for anyone ⑤managing a chronic health condition.

Jiho had always assumed he would join a large corporation after graduation, just as his parents expected. During his final year of university, however, he joined a small student team building an app that connected local farmers directly with restaurants. After nearly failing twice, the team secured a small investment that allowed them to hire their first employee. Looking back, Jiho believes that ___________.

When the body fights off an infection, the immune system relies heavily on adequate sleep to function effectively. During deep sleep, the body produces and releases cytokines, proteins that help regulate immune responses and coordinate the fight against harmful invaders. People who consistently sleep fewer than six hours a night show measurably weaker antibody responses after vaccination compared with those who sleep seven or eight hours, suggesting that _______________. 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. Rather than being a passive state, sleep functions as an active period during which the immune system repairs itself and prepares for future threats.

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. (A) 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. (B) 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. (C) 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.

Not long ago, Junho felt he needed to check his phone every few minutes just to keep up with his friends. (A) During this unplanned break from his phone, he was surprised to discover that he actually felt calmer rather than anxious. (B) Encouraged by this experience, he began setting aside phone-free hours on purpose, gradually growing comfortable with being offline. (C) This constant checking left him drained, until one day his phone battery died unexpectedly during a trip.

Airlines and other companies often invite customers to pay a small extra fee to offset the carbon released by their trips. (A) As a result, purchasing an offset can become a convenient way to avoid making harder, more meaningful changes to one's actual carbon footprint. (B) This option relies on carbon offsets, credits that fund projects like tree planting or renewable energy in exchange for supposedly canceling out one's own emissions. (C) Critics point out, however, that many such projects would have occurred regardless of the funding, meaning the offset achieves little real, additional benefit.

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.

That two- or three-hour gap may look modest on paper, but its effects accumulate quickly, touching everything from mood to memory. 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. ( ① ) Part of the problem lies in biology: as puberty begins, the body's internal clock naturally shifts later, making it difficult for teenagers to fall asleep before eleven at night. ( ② ) Yet school start times rarely adjust to this shift, forcing students to wake before their bodies are ready. ( ③ ) The consequences extend well beyond simple tiredness. Chronic sleep loss during adolescence has been linked to impaired concentration, weakened memory, and a higher risk of anxiety and depression. ( ④ ) It can also disrupt the hormones that regulate appetite, contributing to unhealthy 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 improved grades, better mood, and fewer tardy arrivals. ( ⑤ ) Despite this evidence, changing entrenched school schedules remains a slow and contentious process.

This gap remains even after accounting for factors such as study habits, motivation, and overall intelligence. Researchers who study teenagers have found a strong link between how well students sleep and how well they perform in school. ( ① ) Students who sleep fewer than seven hours a night tend to score lower on tests of memory and attention than those who sleep eight or nine hours, even when the two groups study for the same number of hours. ( ② ) One explanation is that sleep plays an active role in learning: during certain stages of sleep, the brain replays and strengthens information encountered during the day, converting fragile short-term memories into more durable long-term ones. ( ③ ) When sleep is cut short, this consolidation process is interrupted before it can finish, so material that seemed well understood the night before often feels unfamiliar the next morning. ( ④ ) For this reason, some schools have begun rethinking early start times, reasoning that an extra hour of sleep might do more for test scores than an extra hour of studying ever could. ( ⑤ )