Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-66

What makes a train "high-speed"? Generally, these are railway systems that (35) __________ at speeds significantly faster than conventional trains. While a regular passenger train might travel at 120 km/h, the most modern high-speed trains can achieve average speeds of over 250 km/h. They represent (36) __________ major leap in land transportation, connecting cities hundreds of kilometers apart in just a few hours.

This incredible speed is not possible on standard railway lines. High-speed trains require specially built tracks, which are constructed from stronger materials and have gentler curves. This design minimizes friction and ensures stability at high velocities. (37) __________, significant investment is needed to build and maintain this dedicated infrastructure, which is a key characteristic that separates high-speed rail from traditional networks.

Beyond the tracks, the technology of the trains themselves is completely different. Their design is highly aerodynamic, meaning their shape is made to reduce air resistance, much like an airplane. These trains don't use conventional engines; instead, they (38) __________ powerful electric motors and advanced control systems. This technology, which is managed by complex computers, ensures the journey is not only faster but also much smoother than on an older train.

The advanced engineering allows the train (39) __________ with remarkable efficiency and safety. The passenger experience is also a priority, with cabins designed to be quiet and comfortable despite the immense speeds. Everything about these systems is (40) __________, from the braking systems to the signaling technology. A transportation company recently announced that it (41) __________ an even faster model next year, pushing the boundaries of what is possible.

The difference in technology is stark. If conventional trains (42) __________ on these special tracks, they still would not achieve the same performance due to their design limitations. The combination of unique tracks, aerodynamic bodies, and powerful electric propulsion is what truly defines a high-speed train, making it one of the most impressive feats of modern engineering.

It's a common question many people, especially teenagers, ask: “Why should I go to the dentist if my teeth don't hurt?” In Vietnam, as in many places, there's a traditional mindset that you only seek medical or dental help when you feel pain. This reactive approach, however, often leads to more complicated and expensive problems down the road. The idea of visiting a dentist for a 'check-up' when everything seems fine can feel strange, but it is the foundation of modern dental care.

This approach is called preventive dentistry, and its goal is to stop problems before they start. During a regular check-up, a dentist does much more than just look for obvious pain points. They use special tools to find early signs of tooth decay, gum inflammation (gingivitis), and other silent issues. Think of it like maintaining a motorbike: you change the oil and check the brakes regularly to prevent a breakdown, not wait until you're stranded on the side of the road. Regular professional cleanings are also essential because they remove hardened plaque that your toothbrush can't, preventing cavities and keeping your gums healthy.

The consequences of skipping these check-ups can be significant. A tiny, painless spot of decay can grow deeper into the tooth over several months. If left untreated, this small problem will require a much larger filling. If it continues to be ignored, the decay can reach the nerve of the tooth, causing severe pain and requiring a complex procedure called a root canal, or even the removal of the tooth entirely. For a teenager, this is especially critical because these are your permanent teeth, which are meant to last a lifetime.

Fortunately, attitudes towards dental care are beginning to change in Vietnam. An increasing number of people are recognizing the long-term benefits of preventive care. Modern dental chains, for example, are actively promoting the concept of biannual check-ups and cleanings, making professional care more accessible and encouraging a proactive mindset. They educate patients that investing a small amount of time and money now can save them from significant pain—and save their parents from much larger expenses—in the future.

Ultimately, your dentist should be seen as a partner in your long-term health, not just an emergency service for when you're in agony. Making the mature decision to attend regular check-ups is one of the smartest investments you can make for your future self. It’s a simple habit that ensures your smile stays healthy and strong for decades to come.