Trong các câu sau, có bao nhiêu câu là mệnh đề?

a) Hãy học thật tốt!

b) Số thực $x$ là số lẻ.

c) $7-1<5$.

d) Số $21$ là số nguyên tố.

Nội dung nào sau đây không thể hiện vai trò của kế hoạch tài chính cá nhân?

Read the following passage about Asia’s culture and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions

[I] Chemicals are present everywhere in our environment, some of which occur naturally, while others are the result of human activities. [II]. They are found in the air, water, and soil, and can have both positive and negative impacts on the ecosystem. Some chemicals, like nutrients, help support life by promoting plant growth [III]. However, others, especially synthetic chemicals such as pesticides, fertilizers, and industrial waste, can be harmful to both the environment and human health. [IV]

The widespread use of pesticides and fertilizers in agriculture has been a major cause of chemical pollution. When these chemicals are used improperly or excessively, they can wash into rivers, lakes, and oceans, leading to water pollution. This runoff can also contribute to the depletion of oxygen in water bodies, a process known as eutrophication. Eutrophication harms aquatic life, disrupting ecosystems and causing the death of fish and other organisms that rely on oxygen.

Toxic chemicals such as heavy metals (e.g., mercury and lead) pose additional threats to the environment and human health. These substances can accumulate in the food chain, starting from plants and animals in contaminated areas and eventually reaching humans. Long-term exposure to these chemicals can lead to serious health issues, including neurological disorders, cancer, and other chronic conditions. Many countries have established regulations to limit the use of harmful chemicals, but enforcement remains a challenge.

Efforts to reduce chemical pollution involve a combination of government regulations, technological innovations, and public awareness. Governments worldwide have introduced stricter rules on the use of hazardous chemicals and encouraged the development of eco-friendly alternatives. These regulations aim to limit the harmful impact of chemicals on the environment, encouraging industries to adopt safer practices. Environmental organizations play a vital role in monitoring chemical pollution, raising awareness, and advocating for cleaner technologies. They work closely with policymakers to ensure effective enforcement of environmental laws. While progress has been made, ongoing efforts are needed to address emerging challenges and ensure a safer and healthier environment for future generations.

The word "depletion" in paragraph II is OPPOSITE in meaning to ____.

Hệ thống lái bên phải được phân loại căn cứ vào:

Nguyễn Dữ làm quan dưới thời nào?

Cho \(f\left( x \right)=a{{x}^{2}}+bx+c\), \(\left( a\ne 0 \right)\) và \(\Delta ={{b}^{2}}-4ac\). Cho biết dấu của \(\Delta \) khi \(f\left( x \right)\) luôn cùng dấu với hệ số \(a\) với mọi \(x\in \mathbb{R}\).

Cho hình bình hành ABCD. Hai điểm M, N lần lượt là trung điểm của BC và AD. Tìm đẳng thức sai?

Read the following passage about Renewable energy sources and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

          [I] Renewable energy sources, such as solar, wind, and hydroelectric power, have gained global popularity as a sustainable alternative to fossil fuels. [II] Unlike coal and oil, renewable energy generates electricity without releasing harmful emissions, making it a cleaner option for the environment (Jacobson et al., 2017). [III] However, despite the advantages of renewable energy, there are still notable challenges that need to be addressed for it to fully replace traditional energy sources (Ell Abban et al., 2014). [IV]

          One major advantage of renewable energy is its sustainability. Renewable resources, unlike fossil fuels, are naturally replenished and do not deplete over time. For instance, solar power harnesses energy from sunlight, which is virtually endless. In addition, renewable energy contributes to reducing greenhouse gas emissions, which helps combat climate change. Many countries are increasingly investing in renewable technologies to decrease their carbon footprint and meet international climate goals.

          However, renewable energy has certain limitations. One significant issue is its intermittent nature; for example, solar and wind power depend on weather conditions, making it difficult to generate a consistent power supply. This variability can disrupt the energy grid, which relies on a steady supply of electricity to meet demand. Another challenge is the high initial cost of setting up renewable energy facilities. Although prices have decreased in recent years, installing solar panels or wind turbines still requires substantial upfront investment (IRENA, 2019).

          Despite these challenges, advancements in technology are gradually making renewable energy more efficient and accessible. Improved energy storage systems, such as batteries, allow excess power generated during favourable conditions to be stored and used later, ensuring a more reliable energy supply. As technology and infrastructure improve, renewable energy may eventually.

The word "it" in paragraph 1 refers to ____.

Phát biểu nào sau đây về ngôn ngữ lập trình là sai?

Một điện tích q bay vào trong một điện trường đều theo phương vuông góc với đường sức điện. Trong suốt quá trình chuyển động, thế năng điện của điện tích đó

Điện thoại thông minh khác với điện thoại di động thường ở điểm gì?

Tổ chức nào dưới đây là thuộc hệ thống chính trị nước ta?

Nguyên tử của nguyên tố oxygen có 8 electron và 8 neutron. Nguyên tử O có kí hiệu là

Em hãy xác định có bao nhiêu loại tỉ lệ?

You are important to your family, because you fill a special place in your family ____ no one else can fill.

Đâu là trào lưu nghệ thuật dân gian được hình thành ở Việt Nam từ thế kỉ XVI đến XVIII?

Cho hai mệnh đề \(P\): “Tứ giác \(ABCD\) là hình vuông” và \(Q\): “Tứ giác \(ABCD\) là hình chữ nhật có hai đường chéo vuông góc với nhau”.

a) Mệnh đề đảo của mệnh đề “\(P \Rightarrow Q\)” là mệnh đề: “Nếu \(ABCD\) là hình chữ nhật có hai đường chéo vuông góc với nhau thì tứ giác \(ABCD\) là hình vuông”.

Kí hiệu $X$ là tập hợp các cầu thủ $x$ trong đội bóng rổ, $P(x)$ là mệnh đề chứa biến: "$x$ cao trên 180 cm".

Mệnh đề "$\forall x \in X$ , $P(x)$" khẳng định rằng

Sự khác biệt giữa mạng LAN và Internet thể hiện ở yếu tố nào sau đây?