trong dạng bài tính toán với hiệu suất khi nào Nên nhân với hiệu suất khi nào nên chia với hiệu suất ?

Khử 3,6 gam hỗn hợp CuO và Fe2o3 bằng CO dư nung nóng thu được 2,64 gam hỗn hợp 2 kim loại. a) Viết Phương Trình Hoá Học xảy ra. b) Tính Phần Trăm Theo Khối lượng mỗi oxit trong hỗn hợp đầu. c) Dẫn toàn bộ khí sinh ra trên qua dung dịch nước vôi trong. Tính khối lượng chất rắn sau phản ứng nếu H = 80%.

1.Phân tích tác dụng của các biện pháp tu từ được sử dụng trong những câu thơ sau: "Trên trời mây trắng như bông Ở dưới cánh đồng bông trắng như mây Mấy cô má đỏ hây hây Đội bông như thể đội mây về làng" 2.Hai câu thơ sau sử dụng những biện pháp tu từ nào?Phân tích tác dụng của những biện pháp tu từ đó? "Mặt trời xuống biển như hòn lửa Sóng đã cài then đêm sập cửa"

Giúp e với ạ ! Cảm ơn 4 câu thuii

Vẽ mầm NL:Có ai thik xem Tokyo Revengers ko

Tìm GTNN-LN 2. B = 4x² - 4x - 3 3. C = x² - x 4. D = -9x² + 5x - 1 5. E = 2x² - 2xy + y² +6x +2029 6. Cho a + b = 1 Hãy Tìm: MinS = a² + b² MaxP = ab

1. They use coal to heat their house. 2. This well-known historical site will attract many people. 3. He will repair my bike. 4. Visitors will leave umbrellas and raincoats in the cloakroom. 5. They will ban advertisements on TV. 6. Many countries around the world will use solar energy in the future. 7. We will use wind and solar power to solve the problem of energy shortages. 8. Nuclear and hydro power will generate a great deal of energy in the future. 9. The government will launch a campaign for using renewable energy next month. 10. They will increase the tax on petrol next year. GIÚP MIK VS Ạ !

vẽ trà sữa nka >< vẽ =app,khum cần full màu dou,ít nhất là 2 cốc nhá vẽ cs tâm giùm

Vẽ anime nữ đang buồn vì người yêu ko rep tin nhắn trên này rất rất là buồn luôn ớ :((( Tui rảnh nè chat vs tui đi

các trùm tiếng anh giúp mình với I. Choose the best answer among A, B, C, or D. 1. I’d like to borrow this book . _________ it yet ? A. Did you read B. Had you read C. Have you read( Dấu hiệu HTHT) D. Do you read 2. We ____ in this town for a long time. We _________ here sixteen years ago. A. had been / come B. have been / came C. were / came D. are / came 3. No breakfast for Mark, thanks . He _________ breakfast. A. hasn’t eaten B. didn’t eat C. isn’t eating D. doesn’t eat 4. The news came as no surprise to me. I _________ for sometime that the factory was likely to close. A. knew B. had known C. have known D. know. 5. Glenda _________ extremely hard when she was a student. A. worked B. has worked C. was working D. had been worked 6. The world war II _________ in 1939 and _________ in 1945. A. begins / ends B. had begun/ended C. began / ended D. has begun / had ended 7. I’ll see him when he _________ here tomorrow. A. comes B. will come C. has come D. had come 8. The house was very quiet when I got home. Everybody _________ to bed A. have gone B. went C. had gone D. goes 9. Every twelve months, the Earth _________ the Sun. A. circles B. circled C. has circled D. is circling 10. Wars _________ the most terrible. At the moment, wars _________ in some places in the world. A. are / happened B. have been / have been happening C. were / are happening D. are / are happening 11. You can’t see Tom because he _________ A. is working B. was working C. has been working D. had been working 12. I have never played table tennis before. This is the first time I _________ to play. A. try B. tried C. have tried D. am trying 13. Hurry up! Our train _________ at 7 o’clock. We have just a little minutes. A. leaves B. is leaving C. will be leaving D. is going to leave 14. The child is still ill but he _________ better gradually. A. gets B. is getting C. has gotten D. got 15. Don’t bother her. She _________ her violin lesson; she always _________ it in the morning. A. takes / is taking B. takes / takes C. is taking / is taking D. is taking / takes 16. I’ll come to see you before I _________ for the United States. A. leave B. will leave C. have left D. am leaving 17. My friend, Mary, arrived after I _________ for her about half an hour. A. was waiting B. had been waiting C. have been waiting D. have waited 18. The accident _________ when we were on the way to Vung Tau. A. occur B. occurring C. occurred D. had occurred 19. It was midnight. Outside it _________ very hard. A. rains B. is raining C. rained D. was raining 20. When he _________ at the station, his train already _________ A. arrived / left B. arrived / had left C. had arrived / left D. arrives / leaves 21. You _________ your new hat when I _________ you yesterday. A. were wearing / had met B. wore / had met C. wore / was meeting D. were wearing / met 22. When I_________ there, dinner _________ so I had a drink first. A. get / is preparing B. get / has been prepared C. got / had been prepared D. got / was being prepared 23. Andrew_________ the test before so he _________ it very easy. A. did / had found B. had done / found C. was doing / found D. did / was finding 24. While her brother was in the army, Sarah _________ to him twice a week. A. was writing B. wrote C. has written D. had written 25. When I last _________ him, he_________ in London A. saw-has been living B. see-in living C. saw- was living D. have seen- lived 26. I was sad when I sold my car. I _________ it for a very long time. A. am running B. were running C. have been running D. had been running 27. By next month, Laura _________ for the company for twenty years. A. will be working B. will work C. has been working D. will have been working 28. When I last saw John, he _________ and was out of breath. A. was running B. ran C. has run D. had been running 29. Mary ______ in London for 15 years. A. is living B. was living C. has lived D. lives 30. Tim ______ in three movies already. I think he’ll be a star some day. A. has appeared B. was appearing C. had appeared D. is appearing