Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-160

A cantilever is a structural beam (21) __________ is supported at only one end. This unique characteristic allows it to project horizontally into space without any vertical support at its free end. The fixed end, where it connects to a main structure like a wall, must be extremely rigid to provide all the necessary stability for the entire beam. This simple idea is a cornerstone of modern construction and design.

The core principle of a cantilever is that this single point of support must counteract all forces acting upon it. This fixed connection resists both the downward pressure from gravity and the upward bending force that occurs along the beam's length. Engineers must calculate these forces very carefully to ensure the structure is safe and does not fail under pressure.

We see cantilevers in many places. A common example is a balcony (22) __________ to the side of a building. It provides outdoor space without needing columns underneath. Similarly, airplane wings are excellent examples; they are fixed to the plane's body at one end and must support the entire aircraft during flight.

The success of any cantilever design depends on its ability to handle different forces. This includes the beam's own weight and any additional weight placed (23) __________ it, such as cars on a bridge or snow on a roof. This combined weight is known as the structural load. The materials used must therefore be selected for their exceptional strength.

In conclusion, the cantilever is a fundamental concept in engineering. Though it appears simple, its application requires precise calculations to ensure safety. Its ability to create long, unsupported spans makes it an essential tool for architects, allowing for many creative and functional designs in everything from skyscrapers and bridges to something as simple (24) __________ a bookshelf.

Have you ever picked up your phone for a quick check, only to realize an hour has vanished as you scrolled through endless content? [I] This isn't accidental. Modern social media apps are meticulously engineered with "infinite scroll" and "pull-to-refresh" features. [II] Their primary objective is to maximize user engagement and time spent on the platform. Understanding these potent design elements is crucial for regaining control over your digital habits.

The genius, and danger, of infinite scroll lies in its elimination of natural stopping cues. Traditional websites had pages, prompting a decision. Infinite scroll removes this friction, creating a continuous stream of novelty. This design taps into our inherent human curiosity and the brain's reward system. Each new post offers an unpredictable dopamine hit, similar to variable rewards in gambling. The "pull-to-refresh" acts similarly, providing immediate feedback and anticipation, reinforcing the loop and making disengagement difficult. [III]

This phenomenon is particularly evident in Vietnam, where apps like TikTok and Facebook, designed with infinite scroll, enjoy immense popularity. These platforms are integral to daily life for millions, from sharing updates to entertainment. Market research firm Statista consistently reports high app usage times among Vietnamese users, directly reflecting these engaging designs' effectiveness. The seamless, never-ending feed keeps users captivated, often without realizing how much time has elapsed, highlighting the pervasive influence on local digital habits.

For teenagers aged 14-15, this issue is especially pertinent. How often have you planned to check TikTok for just five minutes, only to find yourself still scrolling an hour later? This directly results from how these apps are designed to be inherently addictive. The constant stream of short, engaging content, tailored by powerful algorithms, creates a compelling loop that is challenging to break. Recognizing that these platforms are intentionally engineered to keep you hooked is the critical first step. [IV]

Armed with this knowledge, you can begin managing your screen time more effectively. Understanding how these apps keep you hooked — by exploiting psychological triggers and eliminating natural stopping points — is the foundation for conscious digital consumption. It's about moving from passive consumption to active choice. Acknowledging the design intentions behind features like infinite scroll empowers you to set boundaries and implement mindful usage strategies, ensuring technology serves you, not the other way around.