Đề ôn thi Đề thi vào lớp 10 Trường Phổ thông Năng khiếu môn Tiếng Anh - Mã đề PTNK-136

Natural gas is a fossil fuel and a non-renewable energy source. It is found deep underground in rock formations or associated with other fossil fuels like coal and petroleum. It is a mixture of gases, with the main (21) __________ being methane. This gas is colorless, odorless, and lighter than air. For safety reasons, a chemical is added to give it a distinct smell so that leaks can be detected easily.

Once it is extracted from the ground, natural gas needs to be transported to where it will be used. This is often done through a vast network of underground pipelines. These pipelines can cross entire countries and even continents, delivering the gas to power plants, factories, and residential areas. This system of transport is very efficient for moving large quantities of the fuel.

One of the most common uses for natural gas is for heating and cooking in homes. It is popular because it burns very cleanly and provides instant heat. An energy expert once commented in a report that natural gas was a significant improvement over older fuels like wood or coal for domestic use due to lower emissions. It is used in furnaces to warm houses and in stoves for cooking food.

Natural gas is also a major source of fuel for electricity generation. Power plants burn the gas to heat water, creating steam that turns turbines. If engineers were to build a new power plant today, natural gas would be a strong candidate for the primary fuel. Power companies often (22) __________ this fuel to meet high electricity demand quickly because gas-fired plants can be started and stopped more easily than other types.

In conclusion, natural gas is an important part of our global energy supply. However, its use is often considered (23) __________; it's cleaner than other fossil fuels but still contributes to climate change. Therefore, while it serves as a crucial 'bridge' fuel, many nations are committed to (24) __________ their long-term dependence on it by investing in renewable energy sources like solar and wind power.

Acne is an almost universal experience for teenagers worldwide, making it one of the most common adolescent health issues. During puberty, fluctuating hormones often trigger increased oil production, leading to unwelcome pimples, blackheads, and whiteheads. [I] Many teens find themselves constantly checking their reflection or avoiding social situations because of their skin. Understanding that you're not alone in this struggle is the first step toward managing it effectively and feeling more confident.

So, what exactly causes these breakouts? The primary culprits are often hormones, specifically androgens, which become more active during adolescence. [II] These stimulate sebaceous glands to produce more sebum, a natural oil. When excess sebum mixes with dead skin cells, it can clog pores. These clogged pores become ideal breeding grounds for bacteria, leading to inflammation and the visible red bumps known as acne. While diet, stress, and genetics can also play a role, hormonal changes are typically the main driver for most teenage acne.

While it might seem tempting to try every product on the market, effective teenage skincare often boils down to consistency and simplicity. A good routine involves gentle cleansing twice daily using a mild cleanser to remove excess oil and impurities. Following this with a lightweight, non-comedogenic moisturizer is crucial, even for oily skin, to prevent it from overcompensating. Incorporating treatments with ingredients like salicylic acid or benzoyl peroxide can help unclog pores and kill bacteria. [III] Remember, patience is key; results often take several weeks to become noticeable.

In Vietnam, skincare is a particularly vibrant topic among young people, with many teenagers keenly following advice from popular YouTubers and beauty influencers. These online personalities often review and recommend products, shaping trends. Brands like La Roche-Posay, known for their dermatologically tested formulations, are highly popular for addressing acne concerns. Beyond international names, local Vietnamese brands are also gaining traction, offering accessible and effective solutions. [IV] This active online community highlights a shared desire among Vietnamese youth to find the best ways to care for their skin and achieve a clear complexion.

Ultimately, managing acne is about finding a routine that works for your unique skin and sticking with it. Remember, acne is a temporary phase for most, and focusing on basic, effective care can make a huge difference in how you feel. Don't be afraid to experiment gently with products or, if your acne is severe or persistent, consult a dermatologist. Taking proactive steps to care for your skin can improve its condition and boost your confidence, allowing you to focus on enjoying your teenage years without unnecessary worries.