Các cậu giải thích và làm giúp mình nhé

Dãy chất chỉ gồm các oxit axit là: A. CO, CO2, CaO, Al2O3, N2O5 B. SO3, SO2, MnO, Fe2O3, N2O5 C. FeO, Mn2O7, SiO2, CaO, Fe2O3 D. N2O5, CO2, P2O5, SO2, SiO2

Choose the best answer for the following sentences: 1. "Those eggs of different colors are very artistic. " - "Yes, they ______ in Russia. " A. were painted B. were paint C. were painting D. painted 2. "David is in prison for smoking drugs. " - "He ______ that it was against the law. " A. is telling B. was told C. told D. tells 3. "The maintenance people didn't remove the chairs from the ballroom. " - "Don't worry. They ______ them before the dance begins. " A. will have been moved B. will have moved C. were moved D. moved 4. Gold ______ in California in the 19th century. A. was discovered B. has been discovered C. was discover D. they discovered 5. ______ that military spending is extremely high. A. We are left B. It feels C. It is felt D. We feel that it is 6. All planes ______ before departure. A. will check B. will have checked C. will be checked D. will be checking 7. I wanted ______ by the head of the company, but it was impossible. A. to see B. to be seen C. seeing D. being to see 8. Nancy ______ at Bob's house every night this week. A. has been eaten B. has eating C. is being eaten D. has been eating 9. "Where did you get these old dresses?" - "We ______ them in the old trunk. " A. were found B. finding C. found D. have been found 10. "What happened to the old mail carrier?" - "He ______ to a new neighborhood to work. " A. has sent B. was send C. was sent D. sent

Giải phương trình sau: $\frac{1}{2x-2}$ -$\frac{2x+1}{x²+x+1}$ +$\frac{3}{2x+2}$ =0

Cho a,b,c>0 và a+b+c=4 Cmr (a+b)(b+c)(c+a) ≥(abc) ³

Người ta thả một quả cầu đồng chất vào bình chứa nước thì thấy thể tích cảu quả cầu bị ngập 90% khi ở trạng thái cân bằng biết TLR cảu nước là 10000N/m3 a. Xác định TLR cảu quả cầu b. Người ta tiếp tục đổ thêm dầu vào bình cho tới khi quả cầu bị ngập hoàn toàn, xác định tỉ số giữa phần thể tích của quả cầu bị ngập trong nước với thể tích của quả cầu ngập tro dầu. Khi quả cầu ở trạng thái cân bằng, biết TLR cảu dàu là 8000N/m3 bạn nào giúp mình giải ý b với ( ý a mình tính ra bằng 9000N/m3 không biết đúng không)

Giúp mình nhanh với mình cho hay nhất và 5* ạ In the old days, people (believe) __ that the Earth (be) _________ flat. 186. The street (become) _________ very crowded after 5 pm every day. 187. The rivers (flow) _________ fast today – much faster than usual. 188. Everything is going fine. We (not have) _________ any problems so far. 189. My cousin (just/tell) _________ me about you. 190. I (help) _________ this woman last week. 191. _________ you (see) _________ Nam and Mai recently ? 192. We (eat) _________ this food several times. 193. My father (plant) _________ this tree 6 years ago. 194. He (not make) _________ any mistake yet. 195. What _________ he (do) _________ yesterday ? 196. They (go) _________ home after they (finish) _________ their work. 197. Who (speak) _________ at the meeting last years ? 198. Where _________ you (go) _________ for your holidays last year ? 199. She (not be) _________ here now. She (wash) _________ dishes. 200. Since I (be) _________ sick, I (not go) _________ on a picnic with you. 201. Rice (grow) _________ in tropical countries. 202. I (work) _________ for a computer company since I (graduate) ________ from university. 203. The house was very quiet when I (get) _________ home. Everybody (go) ________ to bed. 204. Mrs. Green always (go) _________ to work by car, but this week she (travel) _________ by bus. 205. I (write) _________ photographs every week. 206. Sorry, I’m late. How long _________ you (wait) _________ ? 207. People (speak) _________ English and French in Canada. 208. Don’t make noise. My mother (talk) _________ to his friends. 209. One day people (travel) _________ to Mars. 210. She’s going out. She (post) _________ these letters. 211. They (go) _________ to the zoo last Sunday. 212. Mai (learn) _________ English for 5 years. 213. His father (work) _________ in this factory since 1990. 214. Jane used to live in Hồ Chí Minh City, but now he (live) _________ in Hà Nội.

Một mảnh đất hình chữ nhật có chiều dài gấp 2 lần chiều rộng và chu vi là 960m.tính chiều dài, chiều rộng và diện tích của mảnh đất trên bản đồ tỉ lệ 1:1000

1.complete the following questions with the words given 1)how/you/go to school 2)when/she/arrive? 3)why / he/eat so much 4)what /they/do yesterday 5)who/you/meet a party? 6)how/ she/come to work this morning? 7)whear/ i /leave my glasses? 8)when/he/get home last night? 9)what/you/do at the weekend? 10) why / she/get angry

Rút gọn biểu thức: a) $x^{}$$(x - 1)^{}$ $-^{}$ $(x + 1) ^{2}$ b) $(x + 3)(x - 3)^{}$ $-^{}$ $(2x - 1)^{2}$