Một đoạn dây dẫn dài 0,80 m đặt nghiêng một góc 60⁰ so với hướng của các đường sức từ trong một từ trường đều có cảm ứng từ 0,50 T. Khi dòng điện chạy qua đoạn dây dẫn này có cường độ 7,5 A, thì đoạn dây dẫn bị tác dụng một lực từ bằng bao nhiêu?

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 they in paragraph 4 refers to _______ .

Tìm m để hàm số y = $\frac{x}{x-m}$ xác định trên khoảng (0; 5)?

Quá trình nguyên phân xảy ra ở loại tế bào nào sau đây?

Nhà sản xuất có thể thu được lợi nhuận cao trong trường hợp nào sau đây?

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.

What is the word “severe” in paragraph 3 is closest in meaning to?

Complete the sentence with the correct form of 'will' or 'be going to'.

A: It's really hot in here.

Thứ tự nào dưới đây đúng với hoạt động của hệ dẫn truyền tim?

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

[I] Sperm whales are fascinating creatures. [II] They possess the biggest brain of any species, six times larger than a human’s, which scientists believe may have evolved to support intelligent, rational behavior. [III] They’re also highly social and capable of making decisions as a group. [IV] But there’s also a lot we don’t know about them, including what they may be saying to one another when communicating with a system of short clicks, known as codas.

Now, new research published in Nature Communications today suggests that sperm whales’ communication is actually much more expressive and complicated than was previously thought. A team of researchers led by Pratyusha Sharma at MIT’s Computer Science and Artificial Intelligence Lab (CSAIL) working with Project CETI, a nonprofit focused on using AI to understand whales, used statistical models to analyze whale codas and managed to identify a structure to their language that’s similar to features of human language. Their findings represent a tool future researchers could use to decipher not just the structure but the actual meaning of whale sounds.

For the study, the researchers examined recordings of 8,719 codas from around 60 whales collected by the Dominica Sperm Whale Project between 2005 and 2018, using a mix of AI algorithms for pattern recognition and classification. The AI then turned the clicks within the coda data into a new kind of data visualization called an exchange plot, revealing that some codas featured extra clicks. These extra clicks, combined with variations in the duration of their calls, appeared in interactions between multiple whales, which they say suggests that codas can carry more information and possess a more complicated internal structure than we had previously believed.

The team’s next step is to build language models of whale calls and to examine how those calls relate to different behaviors. They also plan to work on a more universal system that could be used across species, says Sharma. Taking a communication system we know nothing about, working out how it encodes and transmits information, and slowly beginning to understand what’s being communicated could have many purposes beyond whales. “I think we’re just starting to understand some of these things,” she says. “We’re very much at the beginning, but we are slowly making our way through.”

Which of the following is TRUE about the study discussed in this passage?

Nội dung nào dưới đây không phải nhược điểm của cơ chế thị trường?

Read the following passage about education in Nepal 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. 

A few years ago, amid a record drought, scientists noticed something odd. A few of California’s giant sequoias inside Sequoia and Kings Canyon National Parks were dying in ways no one had ever documented – from the top down. When researchers climbed into the canopies, they discovered that beetles had bored into a few branches. By 2019, at least 38 of the trees had died – not a large number, but "concerning because we’ve never observed this before,” says Christy Brigham, the park’s chief of resource management.

Scientists had assumed that stately sequoias, with their bug-repelling tannins, were immune to dangerous pests. Worried experts are investigating whether some mix of increased drought and wildfire, both worsened by climate change, have now made even sequoias susceptible to deadly insect invasions.

If so, these ancient sentinels would be just the latest example of a trend experts are documenting around the world: Trees in forests are dying at increasingly high rates—especially the bigger, older trees. According to a study in the journal Science, the death rate is making forests younger, threatening biodiversity, eliminating important plant and animal habitat, and reducing forests’ ability to store excess carbon dioxide generated by our consumption of fossil fuels. [A]

There is no single direct cause. Decades of logging and land clearing play a role, scientists say. But increasing temperatures and rising carbon dioxide from the burning of fossil fuels have significantly magnified most other causes of tree death. Scientists are documenting longer and harsher droughts, more severe outbreaks of insects and disease, and increasingly catastrophic wildfires.

With 60,000 known tree species on Earth, those shifts are playing out differently across the planet. In central Europe, for instance, “You don’t have to look for dead trees,” says Henrik Hartmann, with Germany's Max Planck Institute for Biogeochemistry. “They’re everywhere.” In one recent year, following a week of excessive heat, hundreds of thousands of beech trees dropped their leaves. Even in colder regions, “You get a couple of hot years and the forests are suffering,” says Hartmann. “There are individual species that are being driven beyond the threshold of what they can handle.” [B]

Just last year, massive fires marched through a dry Australia, smoldered across 7.4 million acres in northern Siberia, and focused the world’s attention on blazes in the Amazon.

The consequences of all these changes around the world are still being assessed. The first national look at tree mortality in Israel showed vast stretches disappearing, thanks largely to scorching heat and wildfires. [C] In a country largely blanketed by stone and sand, forests mean a great deal. Trees support nests for eagles and habitat for wolves and jackals. They hold soil with their roots. [D]

“We’re dealing with a very tough situation. It’s a race to the unknown,” says Tamir Klein at the Weizmann Institute of Science.

In which space (marked A, B, C and D in the passage) will the following sentence fit?

Without them, plants that normally rise in trees’ shadows are suddenly exposed to higher temperatures and bright light.

Planting trees can contribute to reducing global warming.

Vào mùa khai trường, các cơ sở sản xuất đã đầu tư theo công nghệ in ấn mới để có thêm những sản phẩm văn phòng phẩm sinh động, hữu ích phục vụ thị trường sử dụng bút, thước, tập vở học sinh tại địa phương. Trong trường hợp này, các cơ sở sản xuất đã thực hiện chức năng gì của thị trường?

Internet có lợi ích đối với các hoạt động nào?

Giả sử cường độ ánh sáng I dưới mặt biển giảm dần theo độ sâu theo công thức \(I = {I_o}{a^d}\), trong đó \({I_o}\) là cường độ ánh sáng tại mặt nước biển, a là một hằng số dương, d là độ sâu tính từ mặt nước biển (tính bằng mét). Ở một vùng biển cường độ ánh sáng tại độ sâu 1m bằng 90% cường độ ánh sáng tại mặt nước biển. Giá trị của a là?