Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-96

Many think of quicksand as a deadly trap from movies, where a person sinks completely. However, the reality is less dramatic. Quicksand is not a special soil; it is ordinary sand saturated with water. Because of its properties, you (35) __________ sink completely in it, no matter how much you struggle.

Normally, sand particles are packed together, creating friction that supports weight. When water saturates the sand, often from an underground source, it flows between the particles. This water greatly reduces the (36) __________ between the sand particles. The sand loses its ability to support weight and behaves more like a (37) __________.

The science behind why you float is related to density. Quicksand is a mixture of sand and water, making it much heavier than just water. In fact, your body is less (38) __________ than quicksand, so you will float. (39) __________ means you will only sink to about your waist.

The real danger, therefore, is not sinking but becoming stuck. The dense mixture creates strong suction around your limbs. (40) __________ does panicking make the situation worse, but it also wastes precious energy. Trying to pull a leg out quickly requires the same force needed to lift a small car.

If you are ever in quicksand, stay calm. Avoid sudden movements and (41) __________ your weight over a larger area by leaning back. Move your legs slowly to let water flow around them, reducing the suction. (42) __________, while quicksand is real, it is not the fatal trap movies show.

In many of Ho Chi Minh City's districts, canals that should be scenic waterways have become choked with plastic bags, styrofoam boxes, and household waste. For years, this pollution has been a source of frustration for local residents, who often feel powerless against the overwhelming problem. However, a new wave of environmentalism is rising, not from government offices or scientific laboratories, but from the actions of ordinary citizens who have decided to take matters into their own hands.

Leading this movement is a group known as 'Sài Gòn Xanh' (Green Saigon). Comprised mainly of young volunteers, this group has gained significant attention for its direct-action approach. They wade into the city’s dirtiest canals, often submerged up to their chests in black water, to physically pull out garbage. What makes their work so impactful is their use of social media. By filming their cleanup efforts and documenting the shocking amount of waste they remove, they have been able to reach millions of people online, turning a local problem into a national conversation.

The effect of this public exposure has been profound. The dramatic before-and-after images and videos do more than just show a cleaner canal; they inspire a sense of hope and possibility. They demonstrate that change is achievable, which encourages more people to volunteer or, at the very least, to think more carefully about their own waste disposal habits. This grassroots movement has created a ripple effect, with similar volunteer groups now appearing in other Vietnamese cities, all inspired by the visible success of Sài Gòn Xanh.

However, it is important to view these volunteer efforts with a realistic perspective. While their work provides immediate and visible relief, it is not a permanent solution to the pollution crisis. Experts point out that such cleanups address the symptoms, not the root causes, which include inadequate waste management infrastructure and a lack of widespread public education on recycling and consumption. Without systemic changes led by authorities, the canals are likely to become polluted again over time.

Ultimately, the story of Sài Gòn Xanh is a powerful testament to the impact of citizen action. It highlights that individuals do not have to wait for permission to start improving their communities. While volunteers alone cannot solve the entire problem, they play a crucial role in raising awareness, setting an example, and putting pressure on both the public and policymakers to take more comprehensive and lasting action.