Đề ôn thi Đề thi vào lớp 10 Trường THPT Chuyên KHXH môn Tiếng Anh - Mã đề KHXH-03

Have you ever seen water (35) __________ down a drain? A whirlpool is a much larger and more powerful version of this. These fascinating natural events occur in oceans and rivers, where powerful bodies of water are in motion. They are essentially rotating masses of water, formed by the meeting of hydrological forces beneath the surface.

A whirlpool is most commonly created by the interaction of opposing currents. When one current flows in a certain direction and meets another flowing in the opposite way, (36) __________ energy of this collision needs to go somewhere. (37) __________, the water begins to rotate. This process is similar to how a storm is formed in the atmosphere, but it happens underwater.

This initial rotation creates a vortex, which is a spiraling movement of water around a central point. The water starts (38) __________ faster and faster, pulling everything on the surface towards its center. The depth and power of the vortex depend on the strength of the original currents. Some whirlpools are small and temporary, while others can be incredibly large and persistent.

The force of a large whirlpool is immense. It creates a strong suction effect that (39) __________ anything floating nearby, from small debris to large boats. If a small boat were to get too close, (40) __________ almost impossible to escape the pull. This is why sailors have always been cautious in areas known for strong currents.

In conclusion, a whirlpool is (41) __________. It is a powerful demonstration of nature's forces at work. A famous oceanographer once reported that ancient sailors (42) __________ other mariners for centuries about the dangers lurking in certain waters. These natural wonders are beautiful to observe from a distance but must be respected for their potential danger.

Walking through any modern café or browsing social media in Vietnam, you'll likely see lush green houseplants adorning every corner. This trend is not just about aesthetics; it’s driven by a popular belief that these plants are tiny, natural air purifiers. In cities like Hanoi and Ho Chi Minh City, where concerns about air quality are rising, many young people are bringing plants into their personal spaces, hoping to create a healthier indoor environment. But is the idea that a few potted plants can filter the air in your bedroom based on solid science, or is it more of a hopeful myth?

The origin of this belief is a famous 1989 study conducted by NASA. Scientists were looking for ways to clean the air in sealed space stations. In their laboratory experiments, they found that certain common houseplants were remarkably effective at removing harmful airborne contaminants like benzene and formaldehyde from sealed chambers. This research was groundbreaking and has been cited countless times since, forming the scientific backbone for the 'air-purifying' plant industry. The results seemed to offer a simple, natural solution to indoor pollution.

However, translating these lab results to a typical home or bedroom environment is complicated. The NASA study was conducted in small, hermetically sealed containers with no air exchange. Your room, on the other hand, has constant air circulation from doors, windows, and ventilation systems. Subsequent research by scientists has shown that in a normal-sized room, the rate of air exchange completely overwhelms the slow filtering process of plants. For houseplants to have a significant impact on air quality, you would need an impractically large number of them – perhaps hundreds. While they do absorb some pollutants, the effect is so minimal that it’s often statistically insignificant compared to simply opening a window for a few minutes.

Despite their limited ability to purify air, the case for keeping houseplants is still very strong. The benefits are primarily psychological. Studies have shown that interacting with indoor plants can reduce stress, improve mood, and increase focus and productivity. This phenomenon, known as biophilia, suggests that humans have an innate need to connect with nature. Tending to a plant can be a mindful activity that provides a sense of accomplishment and tranquility. Therefore, while they may not be the powerful air filters we wish they were, their positive impact on mental well-being is undeniable.

In conclusion, the claim that houseplants are effective air purifiers is an oversimplification of the original science. While they do not significantly clean the air in a standard room, they are far from being just useless decorations. Their proven ability to boost mood and reduce stress makes them a valuable addition to any indoor space, contributing to a sense of well-being in a different, but equally important, way.