Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-180

Concrete is an essential material in our modern world, forming the backbone of everything from skyscrapers to sidewalks. It is, by far, the most widely used construction material on Earth. The reason for its popularity lies in its incredible strength, durability, and versatility. While it may seem like a simple grey substance, concrete is actually a carefully balanced composite material, created from a specific recipe of ingredients that have been perfected over many years.

The fundamental recipe for concrete involves three main parts: a paste and an aggregate. The paste consists of Portland cement and water, which, when combined, start a chemical reaction. This paste coats the surface of the aggregate, which is typically a mix of sand and gravel. As the paste hardens, it binds all the individual particles of sand and gravel together into a single, solid mass. This process is what gives concrete its rock-like characteristics.

Achieving the right consistency and strength is a science. Engineers and construction workers must make precise calculations to determine the exact proportions of water, cement, sand, and gravel. Too much water can weaken the final product, while too little can make it difficult to mix and pour. (21) __________ is what ensures the concrete will be able to support heavy loads and last for decades without failing.

Once mixed, the wet concrete must be transported and poured quickly, before it begins to set. It is typically poured into molds or forms, which hold it in the desired shape as it hardens. This initial (22) __________ process can take several hours, but the concrete continues to strengthen for weeks or even months. Only after it has fully cured (23) __________ the structure possess its designed load-bearing capacity and durability.

(24) __________, the journey of concrete from a simple mixture of powder, water, and stones to the foundation of our cities is a testament to human ingenuity. Its simplicity, combined with its immense strength, ensures that it will remain a vital component of construction for the foreseeable future.

Have you ever scraped leftover food into the bin after school lunch, or seen uneaten food after a family dinner? This common scene points to a significant issue: food waste. It’s not just about what's left on your plate; it's about all the food produced, transported, and bought, only to be discarded. While it might seem harmless, the journey of that uneaten food from our plates to the landfill has surprising and far-reaching consequences for our planet. [I]

Globally, the scale of this issue is immense. A staggering one-third of all food produced for human consumption never gets eaten. This isn't just a shame; it's an environmental burden. When food rots in landfills, it produces methane, a potent greenhouse gas contributing significantly to climate change. Beyond emissions, wasting food also means wasting all the precious resources—water, land, energy, and labor—that went into growing, processing, and transporting it. [II]

In Vietnam, food waste is a particularly relevant concern. While we cherish our diverse cuisine, especially during festive periods like Tết, celebrations often lead to increased surplus food that is wasted. Recognizing this, various campaigns and organizations have emerged. For instance, the Food Bank Vietnam actively rescues edible, surplus food from businesses and redistributes it to those in need, highlighting local commitment to addressing this national issue. [III]

Understanding wasted food's journey reveals its true impact. Every item thrown away represents lost energy, water, and effort. It’s food that could have nourished someone, yet instead contributes to landfill expansion and pollution. For young people, this is especially important because it affects the world you will inherit. From the energy consumed to refrigerate unused ingredients to the fuel burned transporting waste, our food choices ripple outwards, influencing resource scarcity and our environment. [IV]

The good news is that we all have a role to play in tackling food waste. Simple actions, like planning meals to avoid overbuying, storing food properly, or creatively repurposing leftovers, can make a big difference. Even choosing smaller portions at meals helps. By being more mindful of what we eat and what we discard, we can reduce our environmental footprint, conserve valuable resources, and contribute to a more sustainable future, one plate at a time.