Cho mệnh đề: "$\forall n \in \mathbb{N}$, $n$ chia hết cho 5".

Mệnh đề phủ định của mệnh đề trên là

Mục đích chính của Mĩ khi thực hiện các chính sách bành trướng, tăng cường ảnh hưởng của mình ở khu vực Mĩ Latinh vào cuối thế kỉ XIX – đầu thế kỉ XX là gì?

1. Do you find yourself yawning all day at school? You probably need more sleep. However, it is not just how much sleep you get that is important. What you do before bedtime also has a huge effect on how you feel the next day. If you spend time chatting to someone on social media, or reading a book on your e- reader, you are not alone.

2. All devices' screens give out a large amount of blue light, which affects the body's production of the sleep hormone, melatonin, which can change your sleep patterns. So it is not just getting to sleep that becomes hard, but the quality of your sleep also suffers. The result is that you can wake up several times during the night, and have difficulty getting up in the morning.

3. Sleep is food for the brain, so not sleeping well can be a severe problem for anyone, especially for teenagers, because their brains are still developing. When you do not sleep well, it can be difficult to concentrate at school, which makes it harder to learn and get good grades. It can also affect your mood, making you feel sad or anxious.   

4. So, it is clear you should not use your phone before you go to sleep. Why not leave it in another room? Nothing on social media is so important that it cannot wait a few hours! You should rediscover paper books and enjoy feeling tired and sleepy before bedtime rather than wondering why your best friend has not liked your photo! How will you wake up? You do not have to use the alarm on your phone. Go and buy yourself an old-fashioned alarm clock! The negative effects that screen time is having on sleep have been in the news a lot recently, so manufacturers of smartphones and tablets have added a feature to the mobile devices that can help reduce these. Most new phones have a night-time setting that changes the colour of the screen so that it gives out less blue light. If you really cannot avoid going onto social media at bedtime, think about turning on this setting on your phone.

Which of the following can be the best title of the passage?  

Đâu là ý đúng: Sợi cacbon nano?

Trong mặt phẳng toạ độ \(Oxy\), cặp vectơ nào vuông góc với nhau trong các vectơ \(\vec a = (2; - 1),\vec b = (3;7),\vec c = (3;1)\) và \(\vec d = (2; - 6)\)?

Read the following passage 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 33 to 40.

Air pollution is a significant environmental issue that affects millions of people worldwide. It results from various sources, including industrial emissions, vehicle exhaust, and the burning of fossil fuels. [I] Among the most harmful pollutants are fine particulate matter (PM2.5), carbon monoxide, sulfur dioxide, and nitrogen oxides. These pollutants not only degrade air quality but also have serious health consequences, such as respiratory diseases, cardiovascular problems, and even premature death. [II]

In major cities, traffic congestion plays a critical role in worsening air pollution. The high concentration of vehicles, particularly those running on diesel fuel, releases large amounts of pollutants into the atmosphere. [III] Additionally, industrial activities in urban areas contribute to the problem by emitting harmful gases and chemicals. [IV]

Governments and environmental organizations have been implementing various measures to combat air pollution. These include promoting the use of renewable energy, encouraging public transportation, and imposing stricter emission regulations on industries. Moreover, advancements in technology have led to the development of electric vehicles and air purification systems, which help reduce pollution levels. However, despite these efforts, achieving clean air remains a global challenge that requires cooperation from all sectors of society.

Which of the following best paraphrases the underlined part in paragraph 3?

Trong trường hợp dưới đây đề cập đến loại hình thất nghiệp nào?

"Do tác động của khủng hoảng kinh tế, hàng hóa sản xuất ra không bán được, công ty X phải thu hẹp sản xuất, khiến nhiều lao động bị mất việc làm".

Dân số thế giới tăng hay giảm là do đâu?

Cho $A=\left[ 1;4 \right],\ B=\left( 2;6 \right)$ và $C=\left( 1;2 \right)$. Xác định $X=A\cap B\cap C.$

Tam giác \(ABC\) vuông tại \(A\) có \(AB = 6\)cm, \(BC = 10\)cm. Tính bán kính \(r\) của đường tròn nội tiếp tam giác đã cho. 

Tập nghiệm của phương trình \(\sqrt {\left( {x - 3} \right)\left( {2 - x} \right)}  = \sqrt {4{x^2} + 12x + 9} \) là:

Nền chuồng được chuẩn bị như thế nào trong quy trình nuôi gà thịt công nghiệp?

Theo nhận định từ các chuyên gia, khả năng công ty của ông A mở một chi nhánh mới ở thành phố X là 40% có thể xảy ra. Nếu đúng như vậy thì khả năng ông A được bổ nhiệm làm giám đốc cho chi nhánh mới này là 80% có thể xảy ra. Xác suất để ông A trở thành giám đốc cho chi nhánh ở thành phố X là bao nhiêu? Làm tròn kết quả đến hàng phần trăm.

Hiện nay, những đồng tiền nào trở thành ngoại tệ mạnh trong hệ thống tiền tệ thế giới?

Read the passage carefully

1. Do you find yourself yawning all day at school? You probably need more sleep. However, it is not just how much sleep you get that is important. What you do before bedtime also has a huge effect on how you feel the next day. If you spend time chatting to someone on social media, or reading a book on your e- reader, you are not alone.

2. All devices' screens give out a large amount of blue light, which affects the body's production of the sleep hormone, melatonin, which can change your sleep patterns. So it is not just getting to sleep that becomes hard, but the quality of your sleep also suffers. The result is that you can wake up several times during the night, and have difficulty getting up in the morning.

3. Sleep is food for the brain, so not sleeping well can be a severe problem for anyone, especially for teenagers, because their brains are still developing. When you do not sleep well, it can be difficult to concentrate at school, which makes it harder to learn and get good grades. It can also affect your mood, making you feel sad or anxious. 

4. So, it is clear you should not use your phone before you go to sleep. Why not leave it in another room? Nothing on social media is so important that it cannot wait a few hours! You should rediscover paper books and enjoy feeling tired and sleepy before bedtime rather than wondering why your best friend has not liked your photo! How will you wake up? You do not have to use the alarm on your phone. Go and buy yourself an old-fashioned alarm clock! The negative effects that screen time is having on sleep have been in the news a lot recently, so manufacturers of smartphones and tablets have added a feature to the mobile devices that can help reduce these. Most new phones have a night-time setting that changes the colour of the screen so that it gives out less blue light. If you really cannot avoid going onto social media at bedtime, think about turning on this setting on your phone.

(Adapted from Prepare)

Which of the following can be the best title of the passage? 

Biện pháp phát triển kinh tế có hiệu quả của nhiều nước ở Mỹ La tinh hiện nay là

Cho parabol \(y = a{x^2} + bx + c\) có đồ thị như hình vẽ dưới đây. Khẳng định nào dưới đây đúng?

Diễn đàn hợp tác châu Á - Thái Bình Dương viết tắt là gì?

Cho hàm số \(y=f\left( x \right)\) xác định trên đoạn \(\left[ -3;2 \right]\) và có đồ thị như hình vẽ sau.

Gọi \(M\) và \(m\) lần lượt là giá trị lớn nhất và giá trị nhỏ nhất của hàm số \(y=f\left( x \right)\) trên đoạn \(\left[ -3;2 \right]\). Khi đó, giá trị \(M-2m\) bằng:

Người tiêu dùng mong điều nào sau đây xảy ra?

Hãy cho biết chu kỳ dao động điều hòa của con lắc đơn không phụ thuộc vào