Cho h = 6,625.10^-34 J.s và c = 3.10⁸ m/s. Một kim loại có công thoát A = 5,68.10^-19 J thì giới hạn quang điện là

a. Sleep is essential for mental and physical well-being, providing numerous benefits to our health.

b. People who do not get enough sleep may suffer from issues such as irritability, poor concentration, and weakened immune function.

c. By allowing the body to rest and the mind to refresh, sleep plays a key role in daily functioning, helping us stay focused and productive.

d. Additionally, insufficient sleep can lead to weight gain and increase the risk of chronic diseases such as heart disease and diabetes.

e. Therefore, ensuring sufficient sleep is vital for improving productivity, mood, and overall quality of life.

Phát biểu nào đúng khi nói về các giai đoạn của quá trình hô hấp ở thực vật?

Cho thông tin sau:

Khu Công nghệ cao Hòa Lạc đã thu hút các dự án sản xuất các sản phẩm công nghệ cao có giá trị gia tăng cao thay thế hàng nhập khẩu và tham gia thị trường thế giới. [...] Về hoạt động ươm tạo công nghệ cao, doanh nghiệp công nghệ cao và đổi mới sáng tạo, đến nay, ngoài Trung tâm Ươm tạo và Đào tạo Công nghệ cao thuộc Ban Quản lý, tại Khu Công nghệ cao Hòa Lạc đã cơ bản hình thành hệ sinh thái đổi mới sáng tạo, tiêu biểu là Trung tâm Đổi mới sáng tạo quốc gia, Trung tâm kỹ thuật hỗ trợ phát triển công nghiệp khu vực phía Bắc thuộc Cục Công nghiệp.

(Nguồn: Báo Đầu tư Online)

Nhận định nào dưới đây là đúng/sai?

Phương án nào sau đây chỉ ra lợi ích của công nghệ đến năng suất lao động?

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 questions from 36 to 42.

In the distance, an enormous, menacing-looking tornado can be seen. Luckily, the area has been evacuated and there is no one to be seen. Then, out of the blue, a few kilometres away a van appears and races down the road straight towards the tornado. Both in their twenties, Joe Hammond and his wife Emma are heading for it. Their purpose is to monitor various characteristics of a tornado, such as its speed, direction, and temperature. The storm chasers are planning to plant themselves directly in the path of the tornado to amass as much information as they can.

Joe and Emma are dedicated storm chasers. They began to chase storms as university students, and in recent years they have been travelling vast distances around the USA in their efforts to locate tornadoes. Bizarre as it may sound, they are not the only people to do it. During the tornado season, hundreds of people cross Tornado Alley, an area between South Dakota and Texas. Their vehicles are almost unrecognisable, as they are concealed underneath an assortment of electronic equipment and contain all manner of communication devices.

When asked why people are so fascinated by tornadoes, Joe said some tornado chasers relish the challenge, while others might just love the exhilaration of being in a treacherous situation. Some experienced chasers have even turned their hobby into a business and set up travel agencies offering tourists trips which guarantee a ringside view of the twisters. It seems, however, that people like Joe and Emma also make a pivotal contribution to the study of tornadoes.

The fact is, although there are about a thousand tornadoes in the USA each year, meteorologists still do not fully comprehend why they happen. This is partly because the research done by radars in laboratories is not as efficacious as mobile equipment deployed directly at the scene. Thus, some research meteorologists even go storm chasing themselves. It seems that the thrill, combined with a desire to understand nature, is the reason why people like Joe and Emma chase tornadoes.

(Adapted from Venture into First for Schools)

The word concealed in paragraph 2 could be best replaced by ________.

Read the passage carefully

1. Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.

2. The explosion in mobile phone use around the world has made some health professionals worried. Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.

3. On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't  agree.

4. What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.

5. As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.

Choose an option (A, B, C, or D) that best answers each question:

What does the word “they” in paragraph 2 refer to?

Mẫu âm thanh sau quá trình lượng tử hóa (biểu diễn giá trị mẫu) là

Hoạt động sản xuất kinh doanh có những vai trò nào?

Một bình nước nóng có công suất 2500 W (hệ số cosφ = 1) và điện áp 220 V. Để chọn dây dẫn từ vật liệu nhôm (mật độ dòng J = 4 A/mm²), cần chọn loại dây có tiết diện hợp lí nhất là

Tiền thân của Liên minh châu Âu ra đời vào năm nào sau đây?