Khối lượng tuyệt đối của một nguyên tử oxygen bằng 26,5595.10^-27 kg. Khối lượng nguyên tử (theo amu) là

Một vòng dây tròn bán kính R, mang dòng điện I. Độ lớn cảm ứng từ tại tâm vòng dây được tính theo công thức

Các hoạt động kinh tế có vai trò trung gian và kết nối sản xuất với tiêu dùng được gọi là gì?

He said that he would take responsibility for his company's damage to the area. But then he denied that.

Các cách nào dưới đây được dùng để nhận biết sự có mặt của nước trong tế bào?

Hàn Mặc Tử sinh ra ở đâu?

Yêu cầu về địa điểm chăn nuôi trong chăn nuôi theo tiêu chuẩn VietGAP là:

Cho hàm số \(f\left( x \right)=\text{tan}x-x\).

Trong mặt phẳng toạ độ \(Oxy\), cho hai điểm \(A( - 1; - 3)\) và \(B(3; - 2)\). Khoảng cách giữa hai điểm \(A\) và \(B\) bằng?

Tính giá trị \(M=A_{n-15}^{2}+3 A_{n-14}^{3}\), biết rằng \(C_{n}^{4}=20 C_{n}^{2}\) (với \(n\) là số nguyên dương, \(A_{n}^{k}\) là số chỉnh hợp chập \(k\) của \(n\) phần tử và \(C_{n}^{k}\) là số tổ hợp chập \(k\) của \(n\) phần tử).

Phương án nào sau đây không thuộc ưu điểm của cơ chế thị trường?

Thiết bị nào không được sử dụng trong nghiên cứu và học tập môn Sinh học?

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions:

            For many people who live in cities, parks are an important part of the landscape. They provide a place for people to relax and play sports, as well as a refuge from the often harsh environment of a city. What people often overlook is that parks also provide considerable environmental benefits.

            One benefit of parks is that plants absorb carbon dioxide - a key pollutant - and emit oxygen, which humans need to breathe. According to one study, an acre of trees can absorb the same amount of carbon dioxide that a typical car emits in 11,000 miles of driving. Parks also make cities cooler. Scientists have long noted what is called the Urban Heat Island Effect: building materials such as metal, concrete, and asphalt absorb much more of the sun’s heat and release it much more quickly than organic surfaces like trees and grass. Because city landscapes contain so much of these building materials, cities are usually warmer than surrounding rural areas. Parks and other green spaces help to mitigate the Urban Heat Island Effect.

            Unfortunately, many cities cannot easily create more parks because most land is already being used for buildings, roads, parking lots, and other essential parts of the urban environment. However, cities could benefit from many of the positive effects of parks by encouraging citizens to create another type of green space: rooftop gardens. While most people would not think of starting a garden on their roof, human beings have been planting gardens on rooftops for thousands of years. Some rooftop gardens are very complex and require complicated engineering, but others are simple container gardens that anyone can create with the investment of a few hundred dollars and a few hours of work.

            Rooftop gardens provide many of the same benefits as other urban park and garden spaces, but without taking up the much-needed land. Like parks, rooftop gardens help to replace carbon dioxide in the air with nourishing oxygen. They also help to lessen the Urban Heat Island Effect, which can save people money.

            In the summer, rooftop gardens prevent buildings from absorbing heat from the sun, which can significantly reduce cooling bills. In the winter, gardens help hold in the heat that materials like brick and concrete radiate so quickly, leading to savings on heating bills. Rooftop vegetable and herb gardens can also provide fresh food for city dwellers, saving them money and making their diets healthier. Rooftop gardens are not only something everyone can enjoy, they are also a smart environmental investment.

Question 36: Based on its use in paragraph 2, it can be inferred that mitigate belongs to which of the following word groups?

Read the passage below and choose A, B, C or D to answer each question from 636 - 640.

Many of the most damaging and life-threating types of weather-torrential rains, severe thunderstorms, and tornadoes-begin quickly, strike suddenly, and dissipate rapidly, devastating small regions while leaving neighboring areas untouched. One such event, a tornado, struck the northeastern section of Edmonton, Alberta, in July 1987. Total damages from the tornado exceeded $250 million, the highest ever for any Canadian storm. Conventional computer models of the atmosphere have limited value in predicting short-live local storms like the Edmonton tornado, because the available weather data are generally not detailed enough to allow computers to discern the subtle atmospheric changes that precede these storms. In most nations, for example, weather balloon observations are taken just once every twelve hours at locations typically separated by hundreds of miles. With such limited data, conventional forecasting models do a much better job predicting general weather conditions over large regions than they do forecasting specific local events.

Until recently, the observation-intensive approach needed for accurate, very short range forecasts, or “Nowcasts”, was not feasible. The cost of equipping and operating many thousands of conventional weather stations was prohibitively high, and the difficulties involved in rapidly collecting and processing the raw weather data from such a network were insurmountable. Fortunately, scientific and technological advances have overcome most of these problems. Radar systems, automated weather instruments, and satellites are all capable of making detailed, nearly continuous observation over large regions at a relatively low cost. Communications satellites can transmit data around the world cheaply and instantaneously, and modern computers can quickly compile and analyzing this large volume of weather information. Meteorologists and computer scientists now work together to design computer programs and video equipment capable of transforming raw weather data into words, symbols, and vivid graphic displays that forecasters can interpret easily and quickly. As meteorologists have begun using these new technologies in weather forecasting offices, Nowcasting is becoming a reality.

Which of the following best paraphrase this sentence:

“With such limited data, conventional forecasting models do a much better job predicting general weather conditions over large regions than they do forecasting specific local events.”

Choose the best answer to fill in the blank (16)

Have you heard about John? He has broken _____with his girlfriend.

Dãy nào sau đây không có giới hạn bằng 0?

Read the passage carefully. Choose an option (A, B, C, or D) that best answers each question from to 646 to 650:

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.

According to paragraph 3, which is TRUE about the salesman?