Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-41

When you look at skyscrapers or long bridges, you might wonder how they can be so strong. A key component behind their stability is the I-beam. While the overall design of a structure is complex, the choice of material is also critical. The I-beam is a fantastic example of smart engineering, providing incredible strength without being excessively heavy. This clever shape allows the beam (21) __________ immense weight, making it essential for modern construction.

The I-beam gets its name from its cross-section, which looks like the capital letter 'I'. An I-beam is (22) __________ two horizontal plates, known as flanges, which are at the top and bottom. These are connected by a thinner, vertical plate called the web. This specific arrangement is not accidental; it is a highly calculated design that maximizes the beam's performance under stress.

The secret to the I-beam's strength lies in how its parts work together. The flanges are far apart, which is important (23) __________ this placement helps resist bending forces effectively. The top flange resists compression, while the bottom flange resists tension. The web connects these two parts and resists shear forces. By concentrating material in the flanges, engineers are creating an incredibly efficient and strong structural element.

The efficiency of the I-beam becomes clear when compared to a solid rectangular beam. If a solid rectangular beam of the same height were used, it (24) __________ significantly more material, making it heavier and more expensive. The I-beam uses material only where it is most needed, removing the less critical mass from the center. This is a perfect example of how the 'less is more' principle rings true in engineering.

Due to its shape, an I-beam, usually made of steel, provides a superior strength-to-weight ratio. An experienced architect once said that he had used I-beams in almost all of his skyscraper designs because they were so reliable and cost-effective. Ultimately, the I-beam is a fundamental building block that combines simple geometry with core engineering principles to build the world around us.

Instant noodles are a global staple, famed for their incredible convenience and affordability. From busy professionals to students burning the midnight oil, these quick meals offer an instant solution to hunger. In Vietnam, their presence is especially profound, with brands like Hảo Hảo and Omachi being household names. It's common to find them in almost every kitchen, readily available for a swift snack after school or during an intense study session, making them an undeniable part of many young people's daily lives.

Despite their widespread appeal, the nutritional profile of instant noodles often raises concerns. Primarily made from refined flour, palm oil, and a multitude of artificial flavors and preservatives, they are typically high in sodium and unhealthy saturated fats. Essential nutrients like protein, fiber, vitamins, and minerals are notably absent. This imbalance means while they might fill you up temporarily, they offer minimal genuine nourishment for a growing body, leaving vital physiological processes unaddressed.

Regular consumption of such an imbalanced diet can lead to several health issues, particularly for developing teenagers. The excessive sodium content contributes to high blood pressure, a condition usually associated with older adults but increasingly seen in younger populations. Furthermore, a lack of fiber and essential nutrients can result in digestive problems, fatigue, and even impact cognitive function, making it harder to concentrate in class or during exams. [I] Relying solely on instant noodles can truly undermine your overall well-being.

Does this mean you should abandon instant noodles entirely? [II] If you must reach for a packet, consider ways to boost its nutritional value. Adding fresh vegetables like leafy greens, carrots, or mushrooms can introduce much-needed vitamins and fiber. Incorporating a source of protein, such as a boiled egg, tofu, or a few slices of cooked chicken, will help you feel fuller and provide essential building blocks for your body.

Ultimately, instant noodles serve as a prime example of how convenience can sometimes overshadow nutritional needs. For 14-15 year olds navigating demanding school schedules and growth spurts, making informed food choices is crucial. [III] While a packet of Hảo Hảo might be a tempting, quick fix, understanding its impact allows you to balance speed with health. Prioritizing varied, nutrient-rich meals will provide the sustained energy and focus you need to excel both academically and personally. [IV]