Kết quả của chương trình sau là gì?

a = "Hello"
b = "world"
 c = a + " " + b
print(c)

Một vật vận tốc 1m/s có động năng 4J. Khi động năng giảm còn một nửa thì vận tốc của vật là

Để kích thích sự ra rễ ở cành giâm, cành chiết người ta sử dụng hoocmôn nào?

Thời kỳ từ lúc nhiễm trùng HIV đến lúc xuất hiện kháng thể trong huyết thanh?

Khí nào dưới đây không phải là nguyên nhân gây nên hiện tương mưa acid?

Tình trạng lạm phát có tác động như thế nào đến các hoạt động sản xuất?

Cấp độ tổ chức sống nào sau đây được xem là cấp độ tổ chức sống cơ bản nhất?

Choose A, B, C or D: No one enjoys ______ in public.

There is no one like you. Without you, your family would not be the same.

Công thức tính moment lực đối với một trục quay

Tại sao vào mùa đông, động vật biến nhiệt sinh trưởng và phát triển chậm hơn?

Nhận định nào sau đây thể hiện trách nhiệm của học sinh trong xây dựng và bảo vệ hệ thống chính trị?

Cơ quan Năng lượng Quốc tế viết tắt là gì?

Nhóm các nước đang phát triển không có đặc điểm chung nào sau đây về phát triển kinh tế - xã hội?

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 23 to 30.

SCREEN TIME: MENTAL HEALTH MENACE OR SCAPEGOAT?

    "Have smartphones destroyed a generation?" Jean Twenge - a psychology professor at San Diego State University - asked in her controversial book, iGen. In the book, she argues that those born after 1995 are facing "a mental-health crisis", and she believes it can be linked to growing up with their noses pressed against a screen. Her newest study provides more support for that connection, showing that teens who spent more than an hour or two a day interacting with their gadgets were less happy on average than those who had more face time with others.

    Twenge's conclusions have come up against criticism in the past. Some have accused her work of oversimplifying or overlooking data that may tell a slightly different story. Twenge recognises that her study suggests only a link between screen use and psychological well-being. A possible explanation is that kids are running to their screens to escape from the things in life that are making them unhappy. However, the surveys can't say whether screen time directly changes teens' mental health, the research states.

    Philanthropist Melinda Gates, whose three children were also born after 1995, wrote in The Washington Post, "phones and apps aren't good or bad by themselves, but for adolescents who don't yet have the emotional tools to overcome life's problems, they can aggravate the difficulties of growing up."

    At the same time, she said, kids are learning on their devices and connecting in novel ways. Other studies have explored the connection between social media and isolation and how "likes" activate the brain's reward centre. Some analyses have found that moderate use of these technologies is not harmful in itself and can even improve children's social skills and build emotional strength.

In which paragraph does the writer discuss the benefits of moderate technology use?

Read the following passage about The Longitude Prize and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions

     On a stormy night in 1707, four ships struck rocks off the south coast of England and sank. [I] One thousand, four hundred sailors were drowned. [II] The ships had crashed because they had no way of knowing how far they had travelled in a particular direction; they could not calculate their longitude, which required accurate time measurement. [III] In such difficult circumstances, they believed that the best response to the disaster was a competition: the Longitude Prize. [IV]

     The Longitude Prize was no ordinary competition. To win it, someone had to find a way of calculating how far a ship had travelled east or west from its point of departure. Geniuses such as Sir Isaac Newton had failed to find a solution, so to ensure the interest of Britain’s greatest scientific minds, the government offered a prize of £20,000 — the equivalent of £2.6 million in today’s money. But to everyone’s surprise, it wasn’t a famous academic who solved the problem, but an unknown carpenter.

     When John Harrison wasn’t working with wood, he was making clocks. An accurate clock would allow sailors to calculate their position, but at the time it was thought impossible to create a mechanical clock that could work on a ship. The movement of the sea and the changes in temperature destroyed the delicate parts. However, after three frustrated attempts, Harrison’s fourth sea clock, H4, finally triumphed. Its mechanics were so good that the H4 worked better than most clocks on land.

   The Longitude Prize and Harrison’s success generated a lot of interest in the 18th century, but it was soon forgotten. However, in 2013, the British government created a new Longitude Prize, offering £10 million to the person who could solve a great challenge to humanity. An enthralled public then took part in a TV programme where viewers chose one challenge from a list of six for scientists to focus on. The question now is, will someone be able to solve it just as well as Harrison solved the challenge presented to him?

Which of the following is TRUE according to the passage?

Dùng một đồng hồ đo thời gian có độ chia nhỏ nhất 0,001 s để đo n lần thời gian rơi tự do của một vật bắt đầu từ điểm A (v_A = 0) đến điểm B, kết quả cho trong bảng dưới đây. Thời gian rơi trung bình, sai số ngẫu nhiên, sai số phép đo thời gian là bao nhiêu? Kết quả đo được ghi như thế nào? Biết sai số dụng cụ là 0,001 s.

Sai số tuyệt đối của phép đo thời gian là

$\Delta t=\overline{\Delta t}+\Delta t_{dc}=$ s.

Kết quả phép đo được ghi như sau:

Ngành nghề liên quan đến Sinh học nào sau đây thuộc nhóm ngành Sinh học cơ bản?

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.