Đốt cháy hoàn toàn m gam sắt trong bình khí oxi thu được 46,4 gam sắt từ oxit. Lập phương trình hóa học của phản ứng. Tính khối lượng sắt tham gia phản ứng. Tính thể tích khí oxi đã tham gia phản ứng. Tính khối lượng KClO3 cần mang đi nhiệt phân để thu được lượng khí oxi ở trên.

Cho hệ phương trình $\left \{ {{3x+y=2m+9} \atop {x+y=5}} \right.$ có nghiệm (x;y). Tìm m để biểu thức (xy + x - 1) đạt giá trị lớn nhất

: : Tìm x, y, z biết: $\frac{x-1}{2}$= $\frac{y-2}{3}$= $\frac{z-3}{4}$và 2x + 3y – z = 50

giúp mình đang cần gấp : Hãy tìm những câu văn có sử dụng phép so sánh trong các bài Bài học đường đời đầu tiên và Sông nước Cà Mau. - Bài học đường đời đầu tiên : + Những ngọn cỏ ... vừa lia qua. + Hai cái răng đen nhánh ... máy làm vieejv. + Cái chàng Dế Choắt ... nghiện thuốc phiện

Ex2. Write sentences, using the correct form of used to 1.We /live/in the countryside when I was a child. ………………………………………………………………………………………. 2.People/ not have/mobile phones 20 years ago. ………………………………………………………………………………………. 3.Jim /go/swimming every weekend? ………………………………………………………………………………………. 4.Lily /not cook/ much, but now she makes dinner every day. ………………………………………………………………………………………. 5.I/go to bed late but not anymore! ………………………………………………………………………………………. 6. There / be/ a supermarket on the corner? ………………………………………………………………………………………. các bạn gioir anh giúp mik với ToT

Câu 5: Thời gian Mã Viện đưa quân tấn công vào nước ta và đầu tiên tấn công ở đâu? A. tháng 4 năm 42. Tấn công ở Hợp Phố. B. tháng 4 năm 42. Tấn công ở Giao Chỉ. C. tháng 4 năm 42. Tấn công ở Cửu Chân. D. tháng 4 năm 42. Tấn công ở Nhật Nam. Câu 6: Hai thứ thuế bị nhà Hán đánh nặng nhất là: A. Rượu và Muối. B. Sắt và Muối. C. Thuế chợ và thuế đò. D. Thuế ruộng và thuế thân. Câu 7: Đây là tầng lớp làm ra của cải, vật chất cho xã hội, họ phải nộp một phần thu hoạch, làm tạp dịch cho các gia đình quý tộc…Họ là ai? A. Nông dân và thợ thủ công. B. Địa chủ và nô tì. C. Nông dân công xã và nông dân lệ thuộc. D. Nô tì và thợ thủ công Câu 8: Khởi nghĩa thất bại, không chịu khuất phục kẻ thù. Bà Triệu đã tuẫn tiết tại: A. Sông Hát (Hát Môn - Hà Nội) B. Núi chùa Thầy (Quốc Oai – Hà Nội) C. Núi Tùng (Hậu Lộc – Thanh Hóa) D. Núi Nưa (Hậu Lộc – Thanh Hóa)

Cho tam giác ABC vuông tại A .Biết AB= 7cm,AC=21cm.Tính các tỉ số lượng giác của góc B và C

CÁC BẠN NHANH TAY NHẬN ĐIỂM NÀO!!!

1. I must go now.I promised _______________ late. (not being / not to be / to not be / I won’t be) 2. Tom ______________ his hand when he was cooking the dinner. (burnt / was burning / has burnt / burns) 3. She asked me _____________ a driving licence. (if I have / whether I have / if I had / whether I have had) 4. Have you decide where ___________for your holidays ? ( going / to go / will you go / you went) 5. The Pyramid of Cheops is one of the seven ____________ of the world. (Pyramids / temples / landmarks / wonders) 6. My father used _______ a lot , but now we stop ___________. (to smoke , smoking / to smoking , smoking / to smoke , to smoke / smoking , smoking) 7. I’m sure _____________there are no trains from HN on Saturday.( if, that, whether, what ) 8. In order to keep fit , we should do exercises _____________. (regular / regularly / regulating / regulation) 9. Many people ___________ that were other wonders , which the ancient Greeks knew nothing about. (blame / wonde / claim / suggest) 10. She is always asking me if the Greet Wall of China ___________ one of the wonders of the world. (is / was / will be / has been) 1. Millions of Christmas cards _____________every year.(send / are sent / are sending / was sent) 2. First prize was awarded _____________ Jackie Stevens , the smallest girl on the team. (with / on / for / to) 3. He had his father ____________his Christmas card.(decorated/decorating/to decorate/decorate) 4. I saw him ______________ the flowers in the garden. (watering / watered / be watered / is watering) 5. Paul is said ____________ the brightest student in the class. (was / to be / being / he was) 6. A contest in which participants have to fetch water from the river is called ___________ contest. (water-fetch / fetching-water / water-fetching / fetch-water) 7. The poem , ____________ by Clement Clarke Moore , became popular in the USA. (that is written / which id written / which was written / that was written) 8. They tried to make a fire by ___________ pieces of bamboo together. (adding / separating / rubbing / taking) 1. When we were in Italy , we spent a few days __________ Venice. (at / on / in / to) 2. They are good friends.They ______________ each other for a long time. (know / have known / knew / were knowing) 3. How about ___________ to Thai Binh Market ? (going / to go / went / gone) 4. “What ____________ in New York ? “ – “It’s very clod and humid” (the weather like / does the weather like / the weather is like / is the weather like) 5. “_______ to come and have dinner with us ? “ – “I’d love to but I’m busy” (Do you like / Would you mind / Would you like / Could you please) 6. Can you tell me where ___________ ?(she does / does she / she is / is she) 7. I was reading while my sisters _____________ with their dolls. (played / were playing / have played / would play) 8. Mount Rushmore _____________ from more than 100 kilometers away. (saw / can see / was seen / can be seen) 9.Geogre showed me some pictures ______by his father .(paint / painting / painted / that painted) 10. We were having dinner when the phone ___________.(ring / rang / was ringing / has rung) 1.What can we do to prevent people ___________ throwing drink cans away ?(in / of / on / from) 2. We haven’t seen each other _________ last January.(for / since / on / in) 3. Are you free ___________ Tuesday evening ? (in / at / on / for) 4. Attempts to___________him failed and he died soon afterward.(revive /return /revise / reward) 5. Compost is a wonderful natural ___________.(substance / material / garbage / fertilizer ) 6. All this unnecessary _________creats so much waste.(pack / package / packing / packaging) 7. We have to get up early ____________ late for class . (so as to be / so that not to be / so as not to be / in order not to be) 8. Chicago is __________ right on the shore of Lake Michigan. (placed / situated / laid / set) 9. We are all _____________ that you passed your English exam.Congratulation! (delighted / relieved / afraid / certain) 10. Excuse me ! I’m doing my homework.______________ turning down your radio a bit ? (Would you mind / Can you / Would you please / Could you)

12.When did you first see him?-> How long ______________________________________ . 14.She last eat this kind of food in 2000. -> She hasn’t _____________________________________________________________ . 15. They held a village festival last week. -> A village festival ________________________________________________________ . 16.They made the fire in the traditional way.-> The fire _____________________________ . 17.They grow hundreds of trees every year.-> Hundreds of trees ______________________ . 18.My sister cleans the house every moring.-> The house____________________________ . 19.They bulit this chuch in 1902.-> This church ___________________________________ . 20.I did my homework last night.-> My homework ________________________________ . 21.Nam wrote these letters.-> These letters _______________________________________ . 22) “Do you know My Son, Nga?” asked Nhi ->Nhi asked Nga __________________________________________________________ . 23) “Is it far from Ha Noi?” ->Nhi asked Nga ____________________________________ . 24) “Is My Son in Quang Nam province?” ->The tourists asked ________________________________________________________ . 25) “Do many people live at My Son?” ->The visitors wanted to know _______________________________________________ . 26) “Do many tourists visit My Son every year?” ->They asked me __________________________________________________________ . 27) “Do you want to visit My Son one day?” ->Nhi asked __________________________________________________________