Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-46

The wheel and axle is one of the six classical simple machines and a cornerstone of modern engineering. At its core, the design is straightforward: it consists of a large circular disc, the wheel, which is firmly attached to a smaller central rod called the axle. When one part turns, the other part turns with it. This simple combination is the basis for countless inventions that shape our world.

The primary purpose of a wheel and axle is to make work easier. One way it achieves this is by making the movement of heavy objects much (35) __________. Imagine trying to drag a heavy box across the floor. Now, imagine putting that same box on a cart with wheels. The cart rolls smoothly because wheels reduce the resistance, or friction, between the object and the ground.

When the large wheel is turned, the narrower axle also (36) __________, but with greater force. This principle is perfectly demonstrated by a common doorknob. A small, gentle turn on the knob (the wheel) generates enough force in the axle to move the latch inside the door. Because of this, you (37) __________ open a heavy door with very little effort. This multiplication of force is a key advantage.

Examples of the wheel and axle are everywhere. From the wheels on a car to the swivel casters on an office chair, the system allows for smooth and (38) __________ movement. The main goal is to (39) __________ friction, allowing objects to roll instead of being scraped across a surface. Even a simple screwdriver works on this principle, where the handle is the wheel and the metal shaft is the axle.

The wheel's large circumference means it travels a greater distance than the axle in a single turn. (40) __________ provides a mechanical advantage, making it a powerful tool. So critical is this invention that (41) __________ could we imagine our modern world without it. (42) __________, the wheel and axle is a simple but brilliant innovation that has been fundamental to human progress for thousands of years.

Inspired by global figures like Greta Thunberg, a wave of environmental consciousness is sweeping across the world, led by its youngest citizens. This powerful youth climate movement is not just a Western phenomenon; it has found a strong and passionate voice in Vietnam. Young Vietnamese are no longer passive observers of environmental issues. They are actively stepping up, organizing, and demanding change, proving that age is not a barrier to making a significant impact on the health of our planet. This is the story of Vietnam’s green generation.

In cities from Hanoi to Ho Chi Minh City, youth-led environmental organizations are becoming increasingly common. Groups like the Green Youth Collective have launched a variety of projects aimed at tackling local environmental problems directly. One popular initiative is organizing community clean-up events in parks, canals, and public spaces, which often suffer from littering. Another key focus is reducing single-use plastic consumption by promoting reusable bags and containers. Their goal is not just to clean up, but to inspire a lasting change in community habits.

Beyond physical clean-ups, this new generation of activists is incredibly skilled at using the power of digital media. They launch social media campaigns on platforms like Facebook and TikTok to raise awareness about issues such as air pollution and deforestation. Through engaging videos, informative graphics, and online challenges, they reach thousands of their peers. One successful campaign, #PlasticFreeVN, encouraged people to share photos of their efforts to avoid plastic. It quickly went viral, showing how online activism can translate into real-world consciousness and action.

The results of these youth-led efforts are becoming visible. Public areas are cleaner, and more cafes and shops are offering eco-friendly alternatives. More importantly, these young activists have started a crucial conversation about environmental responsibility in their communities. However, they also face challenges. Some find it difficult to get consistent support from older generations, and the sheer scale of environmental problems can feel overwhelming. Despite these obstacles, their determination remains strong, fueled by a desire for a sustainable future for their country.

The green generation in Vietnam demonstrates that meaningful change can start with anyone, anywhere. They combine practical, on-the-ground action with modern digital communication to create a powerful movement. By taking responsibility for their local environment, they are not only improving their own communities but also contributing to a global fight for the planet. Their work sends a clear message: the future is in their hands, and they are shaping it to be a greener one.