Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-66

In the vast, colorful world of coral reefs, many creatures form special partnerships to survive. One of the most famous examples of this is the relationship between the clownfish and the sea anemone. They live together and help each other in a partnership that benefits them both. This cooperation is a fascinating display of life in the ocean.

The sea anemone looks like a beautiful flower, but it is actually a dangerous animal. Its tentacles are covered in stinging cells that it uses for protection against predators and to catch its food. For most small fish, swimming too close to an anemone means certain death. The powerful sting paralyzes them quickly.

However, the clownfish is different. It is immune to the anemone’s poison. This allows it to swim freely among the dangerous tentacles. In fact, this partnership is perhaps the best known example of mutualism in the sea. The anemone (21) __________ a safe home for the clownfish, protecting it from larger fish that want to eat it. Other fish simply (22) __________ not get close without being stung.

In return, the clownfish is not just a lazy guest. It helps the anemone by cleaning its tentacles and eating any leftover food scraps. The clownfish also scares away butterflyfish, which are known to eat anemones. The clownfish has a special layer of (23) __________ on its skin that prevents the anemone from stinging it. Rarely (24) __________ an anemone host a fish so comfortably and safely.

In conclusion, the relationship between the clownfish and the sea anemone is a perfect example of how two very different species can depend on each other for survival. The clownfish gets a home and protection, and the anemone gets a cleaner and a guard. They are a classic team, working together in the deep blue sea.

Imagine a time when downloading a song took ten minutes, and using the internet meant your phone line was constantly busy. This was the reality of dial-up internet, the primary way homes connected to the World Wide Web just a few decades ago. Maxing out at a sluggish 56 kilobits per second, dial-up connections relied on standard telephone lines and modems producing distinct squawks. [I]

As the internet evolved from simple text to rich graphics and streaming media, faster connections became essential. This ushered in the era of broadband, initially dominated by DSL (Digital Subscriber Line) and cable internet. DSL utilized existing copper telephone lines more efficiently for higher speeds, often reaching several megabits per second. Cable internet, leveraging coaxial TV cables, offered competitive speeds. [II] These advancements provided "always-on" internet without tying up phone lines, a significant leap towards immersive online experiences.

The true revolution in home internet came with the widespread adoption of fiber optic technology. Unlike copper wires transmitting electrical signals, fiber optic cables use thin glass strands to transmit data as pulses of light. This fundamental difference unlocks unprecedented speeds and capacities, carrying vast amounts of data over long distances with minimal signal degradation. Fiber optic connections offer symmetrical speeds and virtually eliminate latency, making gaming and high-definition streaming incredibly smooth. This engineering forms the backbone of today's fastest internet. [III]

Vietnam, in particular, has witnessed a remarkable digital transformation, moving swiftly from copper to a nationwide fiber optic backbone. State-owned enterprises like VNPT and private giants such as FPT Telecom have led this shift, investing massively in infrastructure. They systematically replaced legacy copper cables with advanced fiber optic networks, extending high-speed connectivity to urban centers and increasingly to rural areas. This rapid deployment has been pivotal for Vietnam's economic development, fostering a vibrant digital economy and connecting millions of households. [IV]

For a 14-15 year old today, slow internet is practically foreign. Your daily life—studying, connecting with friends, immersive gaming, and streaming shows—relies entirely on lightning-fast, reliable internet. This seamless digital experience, often taken for granted, is the direct result of decades of relentless innovation. From noisy dial-up modems to silent light pulses traveling through fiber optic cables, this engineering journey underpins your digital world. Understanding this evolution helps you appreciate the technology that makes your digital life possible.