Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-146

The Earth's oceans represent a vast and potent source of untapped renewable energy. Beyond the familiar power of the sun and wind, the ocean itself provides a consistent force we can harness: the tide. Tidal energy is a method of generating electricity by using the natural rise and fall of sea levels, offering a clean and sustainable alternative to fossil fuels.

This daily movement of water is caused by the gravitational pull of the Moon and Sun. Because the movements of these celestial bodies are known with great accuracy, the resulting tides are extremely predictable. The cycle of high and low tides happens every day without fail, which means we can calculate the availability of this energy source far into the future.

To capture this power, engineers place large underwater turbines in areas with strong currents. These machines, which look similar to wind turbines, are designed to withstand the ocean environment. They must be placed in specific locations, such as estuaries or narrow channels, where the water flow is strongest. As the tide moves in and out, the water turns the blades of the turbines to (21) __________ electricity.

One of the biggest benefits of tidal power is its reliability. It is much more consistent than wind or solar power, which can be affected by changing weather. (22) __________ means that grid operators can depend on a steady supply of energy. Furthermore, the technology is remarkable. Not only (23) __________ it clean and renewable, but its underwater placement also means it has a low visual impact on the landscape.

(24) __________, tidal power is an exciting and growing field of renewable energy. While it is not yet as common as other forms, its potential for providing dependable, clean electricity to coastal regions is enormous. With continued development, the powerful, daily pulse of the ocean could play a key role in our future energy mix.

Walk into any trendy café in Vietnam or scroll through social media, and you'll likely spot them: houseplants. From delicate ferns to towering monsteras, these green companions are a staple in modern décor, especially in cities like Hanoi and Ho Chi Minh City where urban air quality is a common concern. Many, perhaps even you, have embraced this trend, believing these leafy friends not only beautify but also act as tiny, natural air purifiers. But is this popular idea rooted in science, or just a pleasing myth? [I]

The belief in plants' air-cleaning prowess largely stems from a groundbreaking NASA study in the late 1980s. Aiming to purify air in sealed spacecraft, researchers investigated common houseplants. Their findings were impressive: certain plants removed significant amounts of airborne volatile organic compounds (VOCs) like formaldehyde, benzene, and trichloroethylene from controlled, sealed chambers. This research provided the initial scientific backing for the widespread claim that plants could be effective biofilters. [II]

However, the NASA study conditions were far removed from a typical room. Experiments used small, sealed chambers with high pollutant concentrations. In a real home, rooms are vast, air circulates freely, and new pollutants emerge constantly. For plants to significantly impact air quality, you'd need hundreds of them, not just a few on your windowsill. This context is crucial when applying lab results to everyday environments. [III]

While not the super-efficient air filters some hope for, houseplants still offer undeniable benefits. They can subtly increase humidity, beneficial in dry environments. More importantly, studies consistently show that having plants indoors improves mood, reduces stress, and boosts overall well-being. They add a calming aesthetic, create a more natural feel, and can even slightly reduce dust. So, while some shops might promote purifying qualities, their true value often lies more in positive psychological and visual impact.

So, can your houseplant truly clean your room's air? Science suggests their direct impact on purifying large volumes of air in a typical home is minimal compared to mechanical air filters. They aren't tiny, efficient VOC scrubbers. [IV] Plants enhance our spaces, connect us with nature, and undeniably contribute to a healthier, happier environment in other, equally valuable ways. Embrace your green companions for the joy and calm they bring; their true magic might be for your well-being, not solely for your air quality.