Hai quả cầu kim loại nhỏ, giống hệt nhau, mang điện tích 2Q và -Q được đặt cách nhau một khoảng r, lực điện tác dụng lên nhau có độ lớn là F. Nối chúng lại với nhau bằng một dây dẫn điện, sau đó bỏ dây dẫn đi. Sau khi bỏ dây nối, hai quả cầu tác dụng lên nhau một lực điện có độ lớn là

Năm số hạng đầu của dãy số có số hạng tổng quát \({{u}_{n}}=\frac{n}{{{2}^{n}}-1}\) là

Lớp 10A có 45 học sinh trong đó có 23 em thích môn Văn, 20 em thích môn Toán, 12 em không thích môn nào. Tính số em thích cả 2 môn?

Đọc đoạn trích sau:

“Thường thì đến gà gáy sáng Mị ngồi dậy ra bếp sưởi một lúc thật lâu thì các chị em trong nhà mới bắt đầu dậy ra dóm lò bung ngô, nấu cháo lợn. Chỉ chợp mắt được từng lúc, Mị lại thức sưởi lửa suốt đêm. Mỗi đêm, khi nghe tiếng phù phù thổi bếp, A Phủ lại mở mắt. Ngọn lửa sưởi bùng lên, cùng lúc ấy thì Mị cũng nhìn sang, thấy mắt A Phủ trừng trừng, mới biết A Phủ còn sống. Mấy đêm nay như thế. Nhưng Mị vẫn thản nhiên thổi lửa, hơ tay. Nếu A Phủ là cái xác chết đứng đấy, cũng thế thôi. Mị vẫn trở dậy, vẫn sưởi, chỉ biết chỉ còn ở với ngọn lửa. Có đêm A Sử chợt về, thấy Mị ngồi đấy, A Sử đánh Mị ngã ngay xuống cửa bếp. Nhưng đêm sau Mị vẫn ra sưởi như đêm trước. ”

(Tô Hoài, Vợ chồng A Phủ, Ngữ văn 12, tập hai, NXB Giáo dục Việt Nam, 2014)

Văn bản trên đã sử dụng phương thức biểu đạt chính nào?

Nguyên tố X có Z = 12. Khi nguyên tử nguyên tố X nhường đi 2 electron thì tạo thành ion X²⁺ có cấu hình electron là

Cho \(A = \{ n = 2k|k \in \mathbb{N},k \le 3\} \), \(B = \{ n \in \mathbb{N}|n \le 5\} \) & \(C = \{ n \in \mathbb{N}|2 \le n \le 6\} \). Tìm tập hợp \(A{\rm{\backslash }}\left( {B \cup C} \right)\)?

Theo quy định pháp luật, công dân sẽ có quyền:

Read the following passage about Preserving Today's Soundscapes for Future Generations 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.

Sonic time capsules save today's sounds for future people. Scientists capture everyday sounds like streets, birds, and children playing in parks around the world. These recordings help us remember our world before changes. Cities are losing unique sounds as life becomes similar everywhere. Old machines, music, and natural sounds might disappear if not saved. Many important cultural sounds are already lost forever because nobody thought to record them when they still existed.

Sound collectors use microphones to record in different places. They visit forests, oceans, cities, and villages to capture soundscapes throughout different seasons and times of day. They store sounds in digital libraries for years. Museums have rooms for listening to past sounds. These experiences help people understand history in ways books cannot. Some researchers travel to remote locations to record indigenous languages and traditional ceremonies before they vanish from our collective memory.

Climate change is changing world sounds. Melting glaciers, endangered animals, and disappearing languages need saving before they're gone. Researchers believe future people will want to know how our world sounded. These capsules will be important records, like photographs. Scientists study how sounds affect human health. The sounds of nature can reduce stress and improve mental health, which makes preserving natural soundscapes even more important for future generations who may live in highly urbanized environments.

Community projects invite people to record daily sounds. Children learn to listen carefully to the world around them and identify sounds that matter to their community. Old people share recordings from their childhood. People feel emotions when listening to these collections. Artists create music using everyday recordings. These projects help communities protect special sounds for the future. Some cities now have sound preservation policies that protect unique acoustic environments just as they would protect historic buildings or natural landscapes from development.

In which paragraph does the writer mention why researchers are collecting sounds affected by climate change?

Trong các cấp tổ chức của thế giới sống, cấp tổ chức cơ bản là gì?

(1) sinh quyển.    (2) cơ thể.             (3) quần xã.           (4) cơ quan. 

(5) tế bào.            (6) quần thể.        (7) hệ sinh thái.      (8) bào quan.

Một trong những điểm hạn chế của giáo dục, thi cử nước ta ở các thế kỉ XVI đến XVIII là gì? 

Quả cầu nhỏ mang điện tích 10^-9 C đặt trong không khí. Cường độ điện trường tại 1 điểm cách quả cầu 5 cm là

Cho biết có mấy phương pháp điều khiển tốc độ động cơ một pha?

Người ta truyền cho khí trong xilanh nhiệt lượng 100 J. Khí nở ra thực hiện công 70 J đẩy pit-tông lên. Độ biến thiên nội năng của khí là

Trong các thiết bị sau, thiết bị nào không sử dụng tụ điện?

“Phép quân điền”– chính sách phân chia ruộng đất công ở các làng xã được thực hiện dưới triều đại nào?

Read the following passage about food addiction 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.

Few people would disagree that one of the world's most popular dishes is pizza. Twenty-two-year-old Zack certainly wouldn't. He would eat a variety of pizza-based items, including homemade pizza, precooked microwave pizza, and even pizza leftovers from the night before. He was consuming 800kg of pizza a year. As a child, Zack had eaten a wide variety of food. But he became addicted to pizza when he started secondary school. American school meals have often been criticised for the large amount of fast food present on the menu, and pizza is the star dish. Zack even spent all his pocket money on slices of pizza.

Naturally, Zack's family worried about his high-calorie, low-vitamin diet. So did Zack. In an attempt to break his addiction, Zack agreed to appear on a TV programme called Freaky Eaters. Its aim was to encourage food addicts to beat their addictions with the help of a psychologist and nutritionist. It wasn't easy. He had to eat a fish dish, while his brother sat in front of him enjoying... a pizza! However, Zack met the challenge and has never eaten pizza again.

Seventeen-year-old Stacy Irvine's friends visit her and discover that she has been rewarded thousands of free toys from fast food restaurants as a regular customer. Stacy's mother often gave her two-year-old girl a portion of fried chicken in a McDonald's restaurant. [I] Since then, Stacy has refused to eat anything else except for pieces of fried chicken, and as a result, her diet has created serious health. She has been warned that if she doesn't change her diet, she will die. [II] Stacy once collapsed due to lack of vitamins and nutrients and needed to be hospitalised. [III] She insisted that Stacy adopt a healthier lifestyle. However, worryingly, Stacy's mother said that while Stacy was beginning to understand the seriousness of her situation, she couldn't eat anything else but chicken nuggets. [IV]

Twenty-year-old Hanna Little was keen on chips. The only thing that Hanna consumed for fifteen years was one plate of chips after another. Not surprisingly, a diet that contained few nutrients and an excess of fat and carbohydrates could only have negative consequences. And it did because not only did Hanna develop health problems, but she also had to leave her job after collapsing at work. At five, Hanna became addicted to chips and refused to eat fruits and vegetables despite her mother's efforts. Hanna says that she was terrified of tasting the flavour of different types of food and she would feel anxious just at the idea of doing it. Parties, picnics and barbecues with friends and family used to be a nightmare. Furthermore, Hanna was soon seen as 'odd' by her friends' parents.

It wasn't until the age of sixteen that Hanna realised she had Selective Eating Disorder (SED). Despite this new knowledge, no solution was found. It wasn't until she lost her job before she started eating normally. Hanna sought therapy from psychologist Felix Economakis, who used hypnosis, a treatment that none of the doctors that she had seen before had mentioned, to get her to eat fruit after one one-hour session, and since then she has been willing to eat anything.... including chips!

(Adapted from Friends Global)

Which of the following best summaries paragraph 4?

Ý nào sau đây phản ánh không chính xác về đặc điểm của nông nghiệp nước ta cuối thế kỉ XV – đầu thế kỉ XVI?

Hội đồng nhân dân phân cấp theo đơn vị hành chính gồm mấy cấp cơ bản?

Read the following leaflet and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 7 to 12. 

WinMart’s 10th Anniversary Celebration!

Join us at WinMart as we celebrate our 10th birthday with incredible deals just for you! (7)______your loyal support over the past decade, we’re thrilled to announce exclusive offers, discounts, and prizes across every department. From fresh groceries and home essentials to the latest tech(8)_____, we have everything you need at unbeatable prices.

Here's what you can enjoy:

• Up to 50% off on over 1,000 items, including fresh (9)___, electronics, and personal care products.

• Special "Buy One, Get Another at 10%" deals on selected products.

• The chance to win exciting gadgets, appliances, and gift vouchers in our lucky draw.

Don’t miss our interactive events, where customers can enjoy a large (10)______of free samples, fun games, and live demonstrations. Be sure to (11)______for our rewards program for additional discounts and collect points on every purchase.

Celebrate (12)______fantastic year with us at WinMart—visit any store or shop online to grab these limited-time deals!