Cho hình chóp \(S.ABCD\) có đáy là hình vuông cạnh \(a\). Tam giác \(SAB\) đều và nằm trong mặt phẳng vuông góc với đáy. Gọi \(M,N\) lần lượt là trung điểm của \(SB,BC\).

Khoảng cách giữa hai đường thẳng AD và MN là:

Tại sao trước khi ủ để hạt nảy mầm, người ta thường ngâm hạt trong nước một thời gian?

Có bao nhiêu phép ghép các đối tượng đồ họa?

Nhận xét nào dưới đây đúng với phong trào yêu nước Việt Nam cuối thế kỉ XIX?  

Cho hình vuông \(ABCD\) cạnh \(a.\) Tính \(P = \left( {\overrightarrow {AB}  + \overrightarrow {AC} } \right).\left( {\overrightarrow {BC}  + \overrightarrow {BD}  + \overrightarrow {BA} } \right).\) 

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?

Những người tham gia vào các hoạt động của nền kinh tế được gọi là gì?

Rửa xe, đánh bóng vỏ xe là công việc bảo dưỡng cơ bản nào?

Trong hình thức sinh sản sinh dưỡng, cây con không được hình thành từ bộ phận nào?

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.”

Read the following passage about home schooling in the UK 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.

Full-time education in the UK is compulsory from the age of five to sixteen, but this doesn’t have to be in a school. Around 50,000 children are educated at home. This is called ‘homeschooling’.

 Parents take their children out of school for different reasons, like illness and the need for special care, or because the distance to the nearest school may be too far. Some children are simply unhappy at school. Whatever the reason, they’re allowed to study at home, although inspectors regularly check how they are getting on.

 Hayley and Jenny haven’t been to school for two years but they haven’t neglected their studies. Their mother worked out strict timetables for them, with hourly lessons for each day. She’s responsible for teaching them Maths, English, History and French. Their father teaches them Science and Geography. They study all the other school subjects online. ‘We have lessons with Dad in the evenings and at weekends,’ explains Hayley.

 The family’s home is in a remote part of Wales. ‘The girls were fine at school but they spent so much time getting to school, they were too tired to learn, says their mother, Julia”. ‘We had a family conference and in the end we decided to try homeschooling. So far, it’s been a big success, but the girls know that if they want to go back to school at any time, we’ll let them. We follow the normal school program of lessons, and they will take all the normal school exams.’

 There are disadvantages too, of course. ‘Social isolation is something I worry about,’ says Julia. They both seem happy and well-adjusted, but they haven’t really got friends who live locally. But in the summer holidays they go away on trips to summer camps, where they have no trouble mixing with people and making friends.’

According to paragraph 2, which of the following is NOT MENTION as a reason for homeschooling?

Em hãy điền cụm từ thích hợp vào chỗ trống (…..) trong khái niệm sau đây: “Quyền bình đẳng của công dân trước pháp luật nghĩa là mọi công dân, không phân biệt nam, nữ thuộc các dân tộc, tôn giáo, thành phần, địa vị xã hội khác nhau đều ….. trong việc hưởng quyền, thực hiện nghĩa vụ và chịu trách nhiệm pháp lí theo quy định của pháp luật”.

Gen không phân mảnh khác gen phân mảnh ở đặc điểm nào?

Đâu là hệ quả của quá trình xâm thực, bào mòn mạnh mẽ bề mặt địa hình ở miền đồi núi?

Số phân tử có trong 50 g nước tinh khiết là \(X \cdot {10^{24}}\) phân tử. Tìm X, viết kết quả gồm ba chữ số khác không.

Để chúc mừng ngày khai trương, siêu thị X đã tổ chức rất nhiều hoạt động cho khách hàng trong đó có trò chơi vòng quay may mắn. Với mỗi hóa đơn trên 1 triệu đồng, 99 khách hàng đầu tiên sẽ nhận được một vòng tay có đánh số (từ 1 đến 99). Cuối ngày khai trương, siêu thị công khai quay số và tìm được 7 khách hàng có vòng tay số 13, 04, 34, 67, 11, 92, 79 may mắn trúng giải. Khi nhắc đến giải thưởng của khách hàng, MC chương trình đã cung cấp các thông tin như sau:

- Có 1 giải đặc biệt, 1 giải nhất, 1 giải nhì, 1 giải 3 và 3 giải khuyến khích.

- Khách hàng nhận giải đặc biệt cầm vòng tay có con số hàng chục lớn hơn 5.

- Tổng các chữ số hàng đơn vị của 3 khách hàng nhận giải khuyến khích bằng 11.

- Khách hàng nhận giải nhì không cầm vòng tay có số cao nhất hoặc thấp nhất.

- Khách hàng cầm vòng tay số 04 chỉ nhận giải ba hoặc khuyến khích.

- Nếu khách hàng nhận giải ba cầm vòng tay số 04 thì khách hàng nhận giải nhất không cầm vòng tay số 92.

Khách hàng cầm vòng tay số bao nhiêu chắc chắn nhận giải khuyến khích?

Phân tử S₈ có 128 electron, hỏi số hiệu nguyên tử của lưu huỳnh (S) là bao nhiêu?

Đâu là tiêu cực của quá trình khu vực hóa kinh tế đối với các quốc gia?

Theo khả năng hóa gỗ của thân, cây trồng được phân làm mấy nhóm?