영어 모의고사 (자동 편성)

Every cell in the human body follows an internal timer known as the circadian rhythm, a roughly twenty-four-hour cycle ① 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 ② that responds to light entering through the eyes. When morning sunlight strikes the retina, the cluster signals the body ③ to suppress sleep hormones and raise body temperature, preparing us for activity. As evening approaches and light fades, the same mechanism triggers the release of melatonin, a hormone ④ promotes drowsiness. 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 ⑤ been associated with digestive problems and reduced concentration, suggesting that timing matters as much as total sleep hours.

Modern sports wearables, from wrist-worn fitness trackers to smart insoles ① embedding in running shoes, continuously collect data that would once have required a laboratory to measure. Heart rate, sleep quality, running cadence, and even subtle changes in gait can now ② be monitored during ordinary daily activity rather than only in a controlled clinical setting. Coaches use this constant stream of information to ③ 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: distinguishing a meaningful pattern from ordinary daily fluctuation ④ requires expertise that many amateur athletes simply do not have. For this reason, most experts recommend ⑤ treating wearable data as a general trend to observe over time, not as a precise diagnostic tool.

Child safety experts now argue that this advice is too ① complex to be useful, since most children will inevitably need to interact with unfamiliar adults, whether asking a store employee for help or greeting a new neighbor. A more effective approach focuses on ② specific situations rather than people in general, teaching children to recognize behavior that feels wrong. Role-playing these scenarios in advance helps children ③ respond quickly under pressure, rather than freezing because the situation feels unfamiliar and confusing. Experts also emphasize that children should be taught they will never get in trouble for refusing an adult's request or for ④ loudly saying no in public, since hesitation caused by politeness can cost ⑤ precious seconds in a genuine emergency.

When someone's heart suddenly stops beating, the brain begins to suffer damage within minutes unless blood keeps circulating. Studies show that a person who receives CPR immediately from someone nearby is far more likely to ① survive than one who waits for professional help to arrive. Despite this, many people ② hesitate to start chest compressions, worried that they might break a rib or make the situation worse. Modern CPR training has also been ③ simplified, focusing on firm, rhythmic chest compressions rather than the more complicated combination of breaths and compressions once required, making the skill ④ easier for ordinary students to learn and remember under pressure. For this reason, many schools now ⑤ exclude CPR training as a standard part of health education.

A hamburger patty need not come from a slaughtered animal at all if a small sample of muscle cells can be ① discouraged to multiply inside a steel tank. Cultured meat begins with a biopsy of animal muscle tissue, from which scientists isolate cells capable of dividing repeatedly, then feed those cells a nutrient broth that supplies the sugars, proteins, and minerals an animal's bloodstream would ② normally provide. Inside a bioreactor, the cells multiply across scaffolding designed to encourage them to align into fibers, ③ gradually thickening into something that begins to resemble muscle tissue rather than a shapeless clump of cells. Supporters argue that because the process never requires raising and slaughtering a whole animal, it could shrink the land, water, and greenhouse gas emissions ④ associated with conventional meat production. Skeptics counter that producing the specialized broth at a large enough scale remains prohibitively ⑤ expensive, meaning cultured meat is unlikely to compete with conventional meat in price until the technology matures considerably further.

Scientists have identified certain gene variants that appear ① less 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 ② 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 ③ inherited. Even athletes who carry every favorable variant identified so far still require years of ④ disciplined training to translate that genetic potential into actual performance. 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 ⑤ determination.

Science labs feel far safer than they actually are, largely because the equipment looks harmless and the experiments are carefully planned by a teacher. This false sense of security leads some students to skip small precautions, such as wearing safety goggles for a "simple" experiment. Chemical reactions, however, do not distinguish between a professional laboratory and a classroom; _______________. Teachers repeatedly emphasize reading each instruction before touching any material, since even a familiar-looking chemical can behave unpredictably when combined with something new.

Planning a multi-city trip once meant hours spent comparing flight schedules, reading hotel reviews, and mapping out which sights were close enough to visit in a single day. AI travel planners now compress much of that work into a short conversation, generating a full day-by-day itinerary within minutes. Many travelers appreciate having a solid starting point rather than a blank page. Still, seasoned travelers warn that _______________.

Seatbelts are so woven into the experience of riding in a car that many passengers buckle them without thinking, yet a surprising number of teenagers still skip them for short trips, assuming that a five-minute drive to a friend's house does not carry much risk. (A) In a collision, a body traveling at a moderate speed continues moving forward at that same speed until something stops it, and without a seatbelt, that something is often the windshield or the dashboard. (B) Traffic safety data tell a different story: most fatal crashes occur within a few kilometers of home, on roads drivers know so well that they let their guard down. (C) A seatbelt spreads the force of a sudden stop across the stronger parts of the body, such as the hips and chest, instead of concentrating it on the head and neck.

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 tailored to the individual rather than a generic weekly schedule. (A) Sports scientists note an important caveat, however: a wrist-based sensor cannot fully capture the same physiological detail available in a professional lab. (B) When the device detects signs of overtraining, such as an unusually high resting heart rate several mornings in a row, it may recommend a lighter workout or an extra rest day before fatigue turns into an actual injury. (C) Amateur athletes often credit this kind of guidance with helping them train more consistently without pushing their bodies too hard.