Cho tam giác ABC vuông tại A (AB<AC).M là trung điểm của BC.Đường vuông góc với BC tại M cắt AC tại D.Gọi E là điểm đối xứng của D qua A.Chứng minh: a/tứ giác BADM nội tiếp b/BD=BE c/góc EBA=góc AMD d/BC.MC=DC.AC Nhớ vẽ hình giùm mình nha
Cho 10,4 gam oxit kim loại R ở nhóm IIA tác dụng vừa đủ với 800 ml dung dịch HCl 0,65M. Tìm công thức của oxit.
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tính lượng oxi cần dùng và khối lượng sản phẩm tạo thành khí đốt cháy hết: a 54 gam nhôm tính thể tích oxi ở đktc
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Giúp mik nha ai làm mik vote 5 sao
Hấp thụ hoàn toàn 0,5 mol co2 vào dd chứa ba(oh)2 và 0,3 mol naoh thu được m gam kết tủa và dd X chứa các muối . Cho từ từ dd chứa hcl 0,3M và h2so4 0,1M vào dd X thấy thoát ra 3,36 lít co2 đồng thời thu được dd Y . Cho dd ba(oh)2 dư vài dd Y , thu được 29,02 gam kết tủa . Giá trị xủa m là ?
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Cho hình vẽ. Biết các độ dài cùng đơn vị đo. Hãy tính độ dài cạnh BC
Thì hiện tại hoàn thành 1. Khoanh tròn đáp án đúng 1. When ____________ the school? A) have you joined B) did you joined C) did you join D) have you ever joined 2. _____________ in England? A) Did you ever worked B) Have you ever worked C) Worked you D) Didn't you have worked 3. That's the best speech _________ B) I never heard B) I didn't hear C) I used to hear D) I've ever heard 4. He's the most difficult housemate _____________________ A) I never dealt with. B) I never had to deal with. C) I've ever had to deal with. D) I've never had to deal with 5. ______ to him last week. A) I spoke ) I've already spoken C) I didn't spoke D) I speaked 6. _____a contract last year and it is still valid. A) We have signed B) We signed C) We haven't signed D) We have sign 7. ______ from a business trip to France. A) I come back B) I came back C) I never came back D) I've just come back 8. Prices ________ in 1995 but then _____ in 1996. A) rised _ falled B) rose _ fell C) have risen _ have fallen D) rose _ have fallen 9. You ____________ to a word ____________ A) listened _ I haven't said B) didn't listen _ I say C) listened _ saying D) haven't listened _ I've said back 10. I can't believe that ________________ the news. A) you haven't read B) you didn't read C) you don't read D) you read not. 2. Chia động từ thì hiện tại hoàn thành 1. I have not worked today . 2. We (buy)..............a new lamp. 3. We (not/ plan)..............our holiday yet. 4. Where (be/ you)? 5. He (write)..............five letters. 6. She (not/ see)..............him for a long time. 7. (be/ you)..............at school? 8. School (not/ start)..............yet. 9. (speak/ he)..............to his boss? 10. No, he (have/ not)..............the time yet. 3.Chia động từ ở thì hiện tại hoàn thành 1. There is no more cheese. I (eat)……………. it all, I’m afraid. 2. The bill isn’t right. They (make)………….. a mistake. 3. Don’t you want to see this programme? It ………….(start). 4. It’ll soon get warm in here. I (turn)……….. the heating on. 5. ………They (pay)…….. money for your mother? 6. Someone (take)………………. my bicycle. 7. Wait for few minutes, please! I (finish)……………. my dinner. 8. ………You ever (eat)………….. Sushi? 9. She (not/come)…………… here for a long time. 10. I (work…………..) here for three years. 11. ………… You ever …………..(be) to New York? 12. You (not/do) ………….your project yet, I suppose. 13. I just (see)………. Andrew and he says he ……..already (do)………. about half of the plan. 14. I ………..just (decide)……… to start working next week. 15. He (be)…………. at his computer for seven hours. 16. She (not/have) ……………any fun a long time. 17. My father (not/ play)……….. any sport since last year. 18. I’d better have a shower. I (not/have)………. one since Thursday. 19. I don’t live with my family now and we (not/see)…………. each other for five years. 20. I…… just (realize)…………... that there are only four weeks to the end of term. 21. The train drivers (go)……… on strike and they stopped working at twelve o’clock. 22. How long…….. (you/know)………. each other? 23. ……….(You/ take)………… many photographs? 24. (She/ eat)………………. at the Royal Hotel yet? 25. He (live) ………….here all his life.. 26. Is this the second time he (lose)……………. his job? 27. How many bottles………… the milkman (leave) ………….? He (leave) ……….. six. 28. I (buy)…………. a new carpet. Come and look at it. 29. She (write)………….. three poems about her fatherland. 30. We (finish) ……………………three English courses.
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