Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-164

Have you ever wondered how ice can fall from the sky during a storm, even on a warm day? This phenomenon is called hail, and it forms inside very powerful thunderstorms. The process begins with (21) __________ strong upward current of air, known as an updraft. This updraft is the engine that drives the creation of hailstones, pushing water droplets high into the very cold parts of the storm cloud.

The journey of a hailstone starts with a tiny ice pellet. As this pellet is carried upwards by the updraft, it enters a region of the cloud where the air temperature is below freezing. Here, supercooled water droplets, which are still liquid despite the cold, instantly (22) __________ to it upon contact. This adds the first layer of ice. The small hailstone then begins to fall due to gravity.

However, its journey is not over. If the updraft is strong enough, it will push the hailstone back up into the cold region of the cloud. This cycle of rising and falling is repeated many times. Each time the hailstone travels up, a new layer of ice is added, making it bigger and heavier. The updraft must be powerful enough to hold up the growing weight of the hailstone.

Eventually, the hailstone becomes so heavy that the updraft can no longer support it. (23) __________, it finally falls out of the cloud and towards the ground. A meteorologist once explained, 'Repeating this cycle multiple times is what allows hailstones to become so large.' He added that in powerful storms, the hailstones (24) __________ reach the size of golf balls or even larger. If an updraft weren't so incredibly strong, hailstones wouldn't grow so big.

The formation of a very large hailstone requires a perfect balance of temperature, moisture, and powerful updrafts. It’s not something that happens in every thunderstorm. In fact, the creation of a giant hailstone is a once in a blue moon event, requiring a unique and powerful set of atmospheric conditions to come together at just the right moment.

Pollution is a pervasive challenge facing cities worldwide, from overflowing landfills to contaminated waterways. While governments often lead environmental efforts, a powerful movement of ordinary citizens is emerging, taking direct action to reclaim their local environments. These citizen-led groups, driven by passion and a shared vision, are proving that positive change starts at the grassroots level. They transform neglected spaces, cleaning rivers, beaches, and forests, demonstrating that individual commitment, when multiplied, creates significant impact against environmental degradation.

In Vietnam, a striking example of this global trend can be found in Ho Chi Minh City, where the volunteer group 'Sài Gòn Xanh' (Green Saigon) has captured national attention. Known for their courageous efforts cleaning heavily polluted urban canals, their work has become widely publicized on social media, transforming them into local heroes. These vital waterways, once choked with plastic waste, debris, and sludge, are slowly being revitalized thanks to Sài Gòn Xanh’s unwavering dedication. Their visible impact encourages others to join environmental initiatives. [I]

The task undertaken by Sài Gòn Xanh is far from glamorous. Donning protective gear, volunteers often wade through murky, foul-smelling water, battling layers of accumulated garbage. They meticulously remove plastic bottles, discarded furniture, old tires, and organic waste, often under the scorching sun. This arduous physical labor, performed consistently, has yielded remarkable results. Sections of canals that were once ecological dead zones are showing signs of life, with clearer water and reduced odors, a powerful testament to their perseverance. [II]

[III] Their highly visible operations serve as a poignant reminder to the public about the severe consequences of pollution and the importance of responsible waste disposal. By documenting and sharing their work online, they not only inspire new volunteers but also raise crucial awareness, sparking conversations about environmental stewardship. This volunteer spirit fosters a stronger sense of community responsibility, showing how dedicated individuals can ignite widespread change. [IV]

The story of Sài Gòn Xanh offers a crucial lesson, particularly for young people. It powerfully illustrates that you don't need to be a scientist or politician to contribute meaningfully to environmental protection. Every individual, regardless of age or background, possesses the capacity to make a difference. Small, consistent actions – whether volunteering for a cleanup, reducing your own waste, or raising awareness among friends – can collectively lead to profound and visible impacts. Their heroism lies in persistent, collaborative effort to heal their city’s waterways.