영어 모의고사 (자동 편성)

Aerobic exercise, such as jogging, swimming, or cycling at a steady pace, strengthens the heart by forcing it to pump ①larger volumes of blood with each beat. Over weeks of consistent training, the heart gradually enlarges and becomes more efficient, meaning it can deliver the same amount of oxygen to working muscles while beating ②fewer times per minute. This adaptation explains why trained athletes often have a much ③lower resting heart rate than sedentary individuals of the same age. Beyond the heart itself, aerobic activity encourages the body to build new capillaries within muscle tissue, ④worsening the delivery of oxygen and nutrients at a cellular level. Researchers have also found that regular aerobic exercise ⑤reduces inflammation throughout the body and improves the way cells respond to insulin.

Caffeine is the most widely consumed stimulant in the world, prized for its ability to ①sharpen focus and fight off fatigue within minutes of consumption. It works by blocking adenosine, a chemical that gradually builds up in the brain throughout the day and makes us feel ②decreasingly sleepy the longer we stay awake. By occupying the receptors that adenosine would normally bind to, caffeine tricks the brain into feeling alert even when the body has accumulated significant sleep pressure. The effects, however, last far longer than most people realize. Because caffeine can remain active in the bloodstream for five to six hours, a cup of coffee consumed in the late afternoon may still be ③interfering with the ability to fall asleep at midnight. Even when people do not consciously notice difficulty falling asleep, caffeine has been shown to ④reduce the amount of deep, restorative sleep obtained later in the night. For this reason, many sleep specialists advise ⑤avoiding caffeine after early afternoon.

Anthropologist Robin Dunbar proposed a concept now known as Dunbar's number, suggesting that human beings can only maintain about one hundred fifty stable social relationships at any given time. This limit, he argued, comes from the size of the human brain, which restricts how many meaningful connections a person can cognitively manage. In contrast, many social media users today have hundreds or even thousands of online friends and followers, a number far exceeding what Dunbar's research predicts. However, having numerous digital contacts does not necessarily mean that all of these relationships are close or emotionally supportive. Most users, when asked, admit that they interact regularly with only a small fraction of their total followers, while the rest remain largely unnoticed. Therefore, Dunbar's number reminds us that ___________.

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. 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. This is the period most closely associated with physical restoration. REM sleep, by contrast, brings rapid eye movements, near-total muscle paralysis, and brain activity that closely resembles wakefulness. Most vivid dreaming occurs during this stage, and researchers believe _______________. 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.

Generation Z, typically defined as those born between the late 1990s and early 2010s, approaches shopping quite differently from previous generations. Having grown up with smartphones and social media, they research products extensively online before making even small purchases. Unlike older generations, who often valued brand loyalty above all else, many members of Generation Z prioritize a company's values, switching brands easily if one no longer matches their beliefs. They also tend to favor secondhand and resale platforms, viewing sustainability as an important factor rather than an afterthought. Peer recommendations shared through short videos frequently carry more weight than traditional celebrity endorsements. Businesses that fail to adapt to these preferences risk losing an entire generation of potential customers. Consequently, many companies now ___________.

Parents and coaches sometimes worry that heavy resistance training might damage the growth plates in a young athlete's bones, cartilage regions near the ends of long bones responsible for lengthening as a child develops. (A) This concern kept strength training out of many youth programs for decades. (B) However, extensive research over the past twenty years has found little evidence that properly supervised resistance training harms growth plates in healthy children. (C) The actual risk, researchers now believe, arises not from lifting weights itself but from poor technique, excessive load, and inadequate supervision.

Pop-up stores have become a popular way for brands to create memorable experiences. (A) As a result, visitors often feel a stronger emotional connection to the brand than they would from an ordinary store visit. (B) Because these spaces exist only temporarily, customers feel a sense of urgency to visit before the opportunity disappears. (C) Many brands design these spaces to be visually striking, encouraging visitors to share photographs on social media.

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.

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. (A) This clock is regulated primarily by a tiny cluster of neurons in the brain that responds to light entering through the eyes, signaling the body to suppress sleep hormones each morning. (B) As evening approaches and light fades, however, the same mechanism triggers the release of melatonin, a hormone that promotes drowsiness. (C) Because this rhythm evolved around the natural cycle of day and night, modern habits such as artificial light exposure or night shifts can push it out of sync, which has been linked to digestive problems and reduced concentration.

Static stretching, in which a muscle is held at its longest length for an extended period, can actually reduce the muscle's ability to generate explosive force immediately afterward. For decades, athletes were taught to stretch a muscle and hold the position before any competition, believing that this practice alone would prevent injury. ( ① ) Recent research, however, has complicated that assumption considerably. ( ② ) This is especially troubling for sprinters or jumpers who need maximum power right away. ( ③ ) Dynamic stretching, which involves controlled, repeated movement through a joint's full range of motion, appears to prepare muscles for activity without this temporary weakening effect. ( ④ ) As a result, many coaches now recommend saving static stretching for after a workout, while reserving dynamic movements for the warm-up period before intense effort begins. ( ⑤ )