giải phương trình: cos2x.cot(x- π/4)

I. Cho dạng đúng của thì quá khứ đơn. (Supply the correct form of past simple tense.) 1. They really (enjoy) the game last Sunday. 2. (Nguyen, win) the table tennis competition? 3. We (be) in bad mood yesterday, so we lost the game. 4. How many goals (your team, score)? 5. Hai (not, be) in the football team with me. 6. (he, go) to the swimming pool yesterday? 7. He (buy) a new ball last week. 8. Hoang (stop) his bike in front of a sports shop. 9. You (play) cards an hour ago. 10. Jane (not, be) tired after the match. II. Viết lại câu theo thì quá khứ đơn. (Put the sentences into past simple.) 1. We finish all the easy levels of Sudoku. 2. She brings a pair of skating shoes. 3. He isn’t a volleyball player. 4. They’re strong strikers. 5. Does he join our team? 6. Beckham misses the ball. 7. The folk games are the main activity of the festival. 8. It’s not a book about Chinese chess. 9. Karachi teaches Judo. 10. The students are very interested in tug of war. III. Đổi câu sang thể phủ định. (Change the sentences into negative.) 1. Stand up! ................................... 2. Sit down! ................................... 3. Go ahead. ................................... 4. Put on your shoes. ........................................... 5. Move! ................................... 6. Stay with us. .............................. 7. Keep silent. .......................... 8. Close the window for me. ..................................... 9. Step on grass. ......... 10. Wait here.

mấy bn lm đc bài nào thì lm nha lm hết thì càng tốt

.Hỗn hợp E chứa các chất hữu cơ đều no, mạch hở gồm axit (X) đơn chức, ancol (Y) hai chức và este (Z) hai chức. Đốt cháy hết 0,2 mol E cần dùng 0,31 mol O2, thu được 6,84 gam nước. Mặt khác, 0,2 mol E phản ứng vừa đủ với 200 ml dung dịch NaOH 0,8M. Cô cạn dung dịch sau phản ứng thu được một ancol (Y) duy nhất và hỗn hợp gồm hai muối, trong đó có a gam muối A và b gam muối B (MA < MB). Tỉ lệ gần nhất của a : b là. A. 6,5 B. 5,0 C. 5,5 D. 6,0

Vẽ Cái gì tượng trưng cho ý tưởng xanh...

Giúp em 3 bài này vs ạ. Ngắn hoi hihi

Cho hỗn hợp X gồm 3 este đơn chức, mạch hở. Đem đốt cháy m gam X thì cần vừa đủ 0,465 mol O2 sản phẩm cháy thu được chứa x mol CO2. Thủy phân m gam X trong 90 ml dung dịch NaOH 1M (vừa đủ) thì thu được được 8,86 gam hỗn hợp muối Y và một ancol Z no đơn chức, mạch hở. Đem đốt cháy hoàn toàn hỗn hợp muối Y thì cần dùng 7,392 lít (đktc) khí O2. Giá trị x là: A. 0,34. B. 0,40. C. 0,32. D. 0,38.

Bn nao có đáp án bài nghe này k ? NẾU K CÓ MIK SẼ ĐỂ LINK NGHE PHÍA DƯỚI CHỨ K GỬI VÀO ĐÂY ĐC

A.supply the correct form of the verbs in parenthese: 1.She never (stay) up late at night. 2. My mother (plant) flowers in the garden at the moment. 3. Mozart (play) the piano when he (be) three. 4. Why you (leave) the party early last night? 5. I (brush) my teeth every night, but last night I (forget) to brush them. 6. Your father (be) in Ha Noi three weeks ago ? 7. Let's (tidy) our classroom. 8. He (take) his final examination next summer. 9. What he (do) yesterday morning ? 10. The sun (warm) the air and (give) us light. 11.She never (allow) her children to stay up late. 12. My youngest brother (get) a new job a week ago. 13. I like (watch) cowboy movies. 14.Marconi (invent) the radio. 15. The disease (spread) fast now.

GIÚP EM VỚI Ạ EM CẢM ƠN MỌI NGƯỜI NHIỀU ^^ Write one verb in each sentence in the past simple and the other verb in the past perfect. 1. The ambulance HAD LEFT (leave) by the time the reporters GOT (get) to the scene of the accident. 2. Before I ............................................. (meet) Dr. Christian, I ............................................. (see) a number of different specialists. 3. It ................................ (be) only the second time I ............................................. (ever / be) in a helicopter. 4. Up to the moment when Mr. O’Donnell ............................................. (say) ‘You’re fired’, I ............................................. (have) no idea why he wanted to see me. 5. When Tonya ............................................. (finish) eating, she ............................................. (ask) the waiter to bring the bill. 6. Luckily, I ............................................. (just / reach) the end of my essay when the teacher ............................................. (tell) us all to put our pens down. 7. We .................................... (do) everything we had to do by five, so we ....................................... (decide) to go out for a coffee. 8. I ............................................. (want) Mrs. Thomas’s young son to touch my ornaments because I ............................................. (just / clean) them. 9. My mum .......................................... (be) annoyed with me because I ....................................... (forget) to get milk when I was at the shop. 10. I ....................................... (get) Janine a book for her birthday, but she .................................... (read) it before. II. Complete this text with these verbs in the past perfect or past perfect continuous. be /catch/ live /plan/ take break/ have/ make /remove/ worry The telephone call from the police was a shock, but not a complete surprise. Molly (1) ........................................ constantly about the old house lying empty during the two months since her mother went into hospital. She (2) ........................................ to go round and check the empty place, but she (3) ........................................ extra busy at work recently. According to the police, a homeless man (4) ........................................ into the house. They (5) ........................................ him one morning as he was leaving the building with one of her mother’s large paintings. When Molly walked into the house, it was obvious that the man (6) ........................................ there for quite a while. He (7) ........................................ food from the cupboards and throwing empty tins and packages all over the floor. He (8) ........................................ quite a mess. He (9) ........................................ also ........................ several paintings from the walls. Molly decided not to tell her mother because she (10) ........................................ already ........................ enough pain in recent weeks and really didn’t need any more bad news.