영어 모의고사 (자동 편성)

For centuries, dreams have fascinated scientists and philosophers alike, yet no single theory fully ① explains why the sleeping brain generates such vivid and often bizarre experiences. One prominent idea suggests that dreaming helps the brain process emotional experiences, ② replays difficult events in a safe, low-stakes environment so that their emotional intensity gradually fades. Another theory proposes that dreams serve a more practical function, ③ allowing the brain to rehearse responses to threats without any real danger. Still other researchers argue that dreaming is simply a byproduct of the brain organizing memories, with vivid imagery ④ arising as the mind sorts through the day's information rather than serving any independent purpose of its own. Because these theories rest on indirect evidence, none has ⑤ been conclusively proven.

Planning a multi-city trip once meant hours ① 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, ② asking about a budget, a travel style, and a handful of preferences before generating a full day-by-day itinerary within minutes. The tool draws on enormous amounts of data, including flight prices, seasonal weather patterns, and reviews ③ leaving by previous travelers, to suggest a route that avoids obvious scheduling conflicts. Many travelers appreciate ④ having a solid starting point rather than a blank page. Still, seasoned travelers warn that these itineraries can feel oddly generic, often ⑤ steering users toward the same popular landmarks.

For decades, athletes were taught to stretch a muscle and hold the position before any competition, believing that this practice alone would prevent injury. Recent research, however, has complicated that assumption considerably, since static stretching, in which a muscle is held at its longest length for an extended period, can actually _______________. Dynamic stretching, which involves controlled, repeated movement through a joint's full range of motion, appears to prepare muscles for activity without this problem.

Open a music streaming app on any given morning, and a personalized playlist is usually already waiting, assembled overnight from songs the algorithm predicts will match a listener's current mood. Listeners often praise the feature for introducing them to artists they never would have searched for on their own. Musicians, meanwhile, have mixed feelings about this shift in how audiences discover new music. A song that the algorithm decides not to promote may struggle to reach listeners no matter how well it was written, meaning that _______________.

Wearable devices that track sleep have become enormously popular, promising a detailed breakdown of light, deep, and REM sleep each night. (A) Despite these limitations, many users have come to treat the nightly score generated by their device as an objective medical verdict, sometimes experiencing anxiety when the number falls below what they expect, a phenomenon researchers have begun calling orthosomnia. (B) Independent studies comparing wearable data with polysomnography, the gold-standard method used in clinical sleep labs, have found that consumer devices are reasonably accurate at distinguishing sleep from wakefulness but considerably less reliable at identifying specific sleep stages. Some trackers overestimate deep sleep, while others underestimate the amount of time spent in REM sleep, and the margin of error can vary widely between brands. (C) These gadgets typically rely on movement sensors and heart rate monitors to estimate sleep stages, since directly measuring brain activity would require equipment found only in a sleep laboratory. This indirect approach, however, introduces significant uncertainty.

Melatonin is a hormone produced by a small gland deep within the brain, and its release follows a remarkably predictable daily pattern. (A) 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 delay its release and make falling asleep more difficult. (B) 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 decline again as morning approaches. (C) 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 lower-energy state. Because of this signaling role, taking melatonin supplements at the wrong time can shift a person's internal clock in the opposite direction from what was intended.

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.

Turning on automatic captions used to mean settling for garbled text full of obvious errors, but recent speech-recognition models have made same-language captions accurate enough that many viewers now leave them on by default. (A) For viewers who are deaf or hard of hearing, this improvement has quietly transformed everyday access to video content that once required a human transcriber and a considerable amount of time to caption properly. (B) The technology listens to audio, breaks it into individual sounds, and matches those sounds against a massive library of words and phrases to predict what was actually said. (C) The system still stumbles over overlapping speakers, strong accents, and specialized vocabulary, occasionally producing captions that are unintentionally funny.

A growing number of health apps now track steps, sleep, and heart rate throughout the day, quietly building a detailed picture of a user's physical condition without requiring a single visit to a doctor's office. (A) Doctors caution, however, that these apps are designed to detect patterns, not to diagnose illness, and that a worried user should always confirm any alarming reading with a professional. (B) For people living far from specialists or unable to afford frequent checkups, this kind of constant monitoring can feel like a genuine safety net. (C) By comparing this stream of data against patterns drawn from millions of other users, the app's algorithm can flag early warning signs, such as an irregular heartbeat, long before the person notices anything unusual.

Shoppers use it to find where an item seen on the street can be purchased, while students use it to identify plants, insects, or historical artworks in seconds. Instead of typing keywords into a search bar, a growing number of people now simply upload a photo and let an algorithm figure out what it contains. ( ① ) This process, known as reverse image search, compares the visual patterns in a picture against a massive database, identifying everything from a landmark in the background to the exact model of a pair of sneakers. ( ② ) The system works by breaking an image down into countless small features, such as edges, colors, and shapes, then matching that pattern against millions of stored examples. ( ③ ) It is not flawless, however. ( ④ ) A blurry photo, an unusual camera angle, or an object partly hidden behind another can easily confuse the algorithm, leading to search results that have nothing to do with the original picture at all. ( ⑤ )