Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-60

Have you ever wondered why structures like cranes or bridges are so incredibly (35) __________? The secret often lies in a simple shape: the triangle. In structural engineering, not all shapes are equal. The triangle has a unique property that makes it essential for building stable structures, which is why engineers rely on it.

To understand this, first consider a square. If you push on a square frame, its corners bend easily, and it distorts into a diamond shape because its angles are not fixed. This tendency to deform can lead to structural (36) __________. Due to this weakness, squares are less reliable for bearing heavy loads without extra support.

A triangle behaves very differently. When force is applied, it is distributed along the sides. This inherent rigidity makes the triangle the (37) __________ geometric shape for building. Its fixed angles mean the structure resists deforming under pressure. Unlike a square, its angles (38) __________ simply change to absorb force; the sides must either compress or stretch.

This principle is visible everywhere. The sides of the triangle work together to distribute the load. (39) __________ is why you see networks of triangles in bridges and roof trusses. These structures (40) __________ the ability to support enormous weight over long distances, ensuring safety. Even bicycle frames use triangles to create a strong, lightweight body.

(41) __________ is this principle important for bridges, but it is also crucial for everything from radio towers to stadium roofs. The strength lies not in the material alone, but in the shape itself. (42) __________, the simple triangle is a cornerstone of safe and efficient engineering design.

In the bustling cities of the 21st century, we are surrounded by a constant symphony of sounds: the roar of traffic, the buzz of construction, and the chatter of crowds. While we often dismiss this as the normal soundtrack of urban life, scientists and health experts are increasingly warning us about an invisible threat: noise pollution. Unlike other forms of pollution, you can't see or smell it, but its effects on our well-being are significant. In Vietnamese cities like Hanoi and Ho Chi Minh City, this issue is particularly acute, with the incessant honking of vehicle horns and blaring promotional loudspeakers forming a familiar, yet stressful, part of daily existence.

The health consequences of prolonged exposure to high levels of noise are well-documented and far-reaching. The most immediate effect is stress. The body interprets loud, unpredictable noise as a danger signal, triggering a 'fight or flight' response that releases stress hormones like cortisol. Over time, this chronic stress can lead to serious cardiovascular problems, including high blood pressure and an increased risk of heart disease. Furthermore, noise pollution is a major disruptor of sleep. Even if you don't fully wake up, noise at night can prevent you from reaching the deep, restorative stages of sleep, leaving you tired and irritable the next day. These effects are detrimental to both physical and mental health.

Beyond general health, noise pollution has a profound impact on cognitive functions, especially those essential for learning. Numerous studies have shown that students in noisier environments struggle more with concentration, memory retention, and reading comprehension. The constant background noise makes it difficult for the brain to filter out irrelevant information and focus on academic tasks. These effects are particularly concerning for young people, as consistent exposure to noise can hinder their academic development and long-term potential. Essentially, a noisy journey to school or a loud neighborhood can create an invisible barrier to effective learning.

Recognizing this problem, authorities in Vietnam have taken some steps to mitigate the issue. For instance, Decree 100/2019/ND-CP imposes penalties on drivers who misuse their horns, especially in urban areas or during night hours. However, the enforcement of such regulations can be challenging, and the deeply ingrained culture of using horns for communication persists. Similarly, while rules exist to control the volume of promotional loudspeakers, they are often ignored, contributing to the overall sonic chaos of the city. These specific local factors compound the universal challenges of managing urban noise.

Tackling noise pollution requires a multi-faceted approach. Better urban planning that separates residential areas from major noise sources, the promotion of quieter electric vehicles, and stricter enforcement of existing laws are all crucial government-led strategies. On an individual level, people can take small steps such as using noise-canceling headphones or advocating for quieter communities. Addressing the invisible pollution of noise is not just about seeking peace and quiet; it's a vital public health imperative for creating healthier, more productive cities for future generations.