영어 모의고사 (자동 편성)

Melatonin is a hormone produced by a small gland deep within the brain, and its release follows a remarkably ①unpredictable daily pattern. Levels stay low throughout the bright hours of the day, begin rising in the evening as darkness falls, peak in the middle of the night, and then ②decline again as morning approaches. This rhythm is controlled primarily by light: specialized cells in the eye detect brightness and send signals that either permit or suppress melatonin production, which is why exposure to bright screens late at night can ③delay its release and make falling asleep more difficult. Unlike some hormones that directly cause the body to perform a task, melatonin does not force sleep to occur; instead, it signals to the rest of the body that night has arrived, preparing various systems to shift into a ④lower-energy state. Because of this signaling role, taking melatonin supplements at the wrong time can shift a person's internal clock in the ⑤opposite direction from what was intended.

People often recognize, in ①calm reflection, that their future selves will be tempted to abandon a goal they currently value. Rather than relying solely on willpower at the critical moment, they may choose to restrict their own future options in advance, a strategy known as precommitment. By making certain choices ②affordable, inconvenient, or impossible to reverse, individuals can protect a long-term goal from a short-term impulse that has not yet arisen. A person hoping to save money might lock funds into an account that ③penalizes early withdrawal, removing the very temptation that would otherwise be difficult to resist. Similarly, someone determined to finish a project might ④publicly announce a deadline, transforming private intentions into a commitment that carries social consequences if broken. What unites these examples is a simple insight: because future desires cannot always be ⑤trusted, the wisest moment to act may be now.

Sleep hygiene refers to a set of simple daily habits that help the body prepare for consistent, restorative rest. Experts commonly recommend going to bed and waking up at the same time every day, even on weekends, because an irregular schedule confuses the body's internal clock and makes it harder to fall asleep on demand. They also advise reserving the bedroom for sleep alone, since using the bed to study, scroll through a phone, or watch videos teaches the brain to associate that space with wakeful activity rather than rest. Physical environment matters as well: a cool, dark, and quiet room tends to produce deeper sleep than one that is warm, bright, or noisy. None of these individual habits guarantees a good night's sleep on its own, but together they form a routine that _______________, much the way a consistent set of cues trains an athlete's body to perform at a certain time each day.

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. When the device detects signs of overtraining, it may recommend a lighter 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 consistently without pushing their bodies too hard. Sports scientists note an important caveat, however: _______________.

Coaches have traditionally focused athlete preparation on training volume and nutrition, but a growing body of research suggests that sleep deserves equal attention. (A) In response, many professional teams now employ sleep specialists who design travel schedules, control bedroom lighting and temperature, and even adjust competition start times when possible. (B) 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. (C) During deep sleep, the body releases growth hormone, essential for repairing muscle tissue, while the brain consolidates motor skills practiced earlier that day into more stable, efficient patterns.

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.

Many people struggling to fall asleep in noisy environments turn to white noise machines, devices that emit a steady, uniform sound covering a broad range of frequencies. (A) Without this masking effect, an abrupt change in sound is far more likely to trigger a brief awakening, even if the sleeper does not consciously remember it the next morning. (B) The appeal lies in a phenomenon called auditory masking, in which a constant background sound makes sudden noises, such as a slamming door, less noticeable to the sleeping brain. (C) However, researchers caution that the benefit depends heavily on volume and consistency, since noise that is too loud or unpredictable can itself become a source of disruption rather than a remedy.

This eagerness to get moving is understandable, but it can come at a real physical cost. Physical education class often feels like the one period of the day when students can finally move freely, which sometimes leads them to skip the warm-up routine that teachers insist on before any real activity begins. ( ① ) Cold muscles, however, are noticeably less flexible than warmed ones, and stretching a stiff hamstring or ankle too quickly can cause a strain that keeps a student off the field for weeks rather than minutes. ( ② ) Coaches often compare an unwarmed muscle to a cold rubber band that snaps rather than stretches under sudden pressure. ( ③ ) Beyond warming up, wearing proper footwear matters more than most students realize; running in worn-out sneakers with little grip left on the sole significantly raises the chance of a twisted ankle on a gym floor or an outdoor field. ( ④ ) Reporting a minor pain immediately, rather than pushing through it to finish a game, also prevents a small issue from becoming a repeated injury that lingers for an entire season. ( ⑤ )

Ordinary evidence cannot help here, since any proof gathered through the senses would itself be generated by the same simulation being tested. Suppose a mad scientist removed a living brain from its body, placed it in a vat of nutrient fluid, and connected its neurons to a supercomputer capable of generating perfectly realistic sensations. ( ① ) The brain would experience a full and convincing world, complete with a sky, a body, and other people, without ever suspecting that none of it existed outside the simulation. ( ② ) This scenario, unsettling as it sounds, raises a genuinely difficult question for anyone confident in their own perception: how could a person ever prove that they are not that very brain right now? ( ③ ) Some philosophers conclude that absolute certainty about the external world is simply unattainable. ( ④ ) Others argue, however, that the mere possibility of deception, however vivid, is not sufficient reason to abandon our everyday trust in what we perceive. ( ⑤ ) Ordinary caution, after all, can never fully settle which side is correct.

Whenever a user marks a message as spam or rescues a message mistakenly filtered out, that action becomes new training data, sharpening the filter's future decisions. Every day, email providers quietly block billions of unwanted messages before they ever reach a user's inbox, a task that would be impossible without an AI filtering system running constantly in the background. ( ① ) The filter examines each incoming message for suspicious patterns, including certain keywords, unusual sender addresses, and formatting tricks that scammers commonly rely on to slip past detection. ( ② ) What makes the system effective is that it keeps learning after launch. ( ③ ) This creates a constant back-and-forth, since spammers study which messages get blocked and then adjust their wording to slip through again. ( ④ ) As a result, spam filtering is less like a fixed wall and more like an ongoing contest, with each side continuously adapting to outsmart the other. ( ⑤ )