Đáp án:
Giải thích các bước giải:
ý đúng D
giải thích luôn có 2 mach nhánh ở3-5 mà mạch 3 có C2H5 là đietyl còn mạch 5 có thêm 2 metyl (CH3) và tổng mạch là heptan
ý A sai vì mạch là heptan
ý B sai vì chỉ có 1 CH3
ý C sai vì giống ý A
ý D đúng vì chọn mạnh dài hơn nên có 2 CH3 ở mạnh 5
`D`
Chọn mạch chính là mạch `C` dài nhất và nhiều nhánh nhất như hình
=> Tên mạch là $heptan$
=> Loại $A, C$
Đọc từ phía có nhiều nhánh hơn => Từ trái sang phải
$=> 5-etyl-3,3-đimetylheptan$
=> Chọn `D`
Mng giúp e nhanh vs ạ e đang cần gấp
4. Choose the correct answer. 1. Was Tom there when you arrived?” - “Yes, but he home soon afterwards.” A. goes B. went C. had gone D. were going 2. Before Jennifer won the lottery, she any kind of contest. A. hasn’t entered B. doesn’t entered C. wasn’t entering D. hadn’t entered 3. “Who was the woman in red dress? Did you know?” - “No, I who she was. I her before.” A. didn’t know - hadn’t seen B. didn’t know - hasn’t seen C. hadn’t known - hadn’t seen D. don’t know - hasn’t seen 4. It’s two years Joe. A. that I don’t see B. that I haven’t seen C. since I didn’t see D. since I saw 5. The man sitting next to me on the plane was nervous because he before. A. hasn’t flown B. didn’t fly C. hadn’t flown D. wasn’t flying 6. They in Scotland for ten years. Now they live in London. A. lived B. have lived C. has been living D. had lived 7. As soon as Laura the house, it started to rain. A. has left B. was leaving C. had left D. had been leaving 8. Sorry we’re late, we the wrong turning. A. had taken B. were talking C. took D. are talking 9. We in New York for ten years and then we here in 1987 A. have lived - moved B. lived - moved C. lived - had moved D. had lived – moved 10. When Martin the car, he took it out for a drive. A. had repaired B. has repaired C. repaired D. was repairing 11. We them before the reception yesterday. A. haven’t met B. hadn’t met C. didn’t meet D. wouldn’t meet 12. Karen didn’t want to come to the cinema with us because she the film. A. has already seen B already had seen C. had already seen D. saw 13. The man looked familiar. I him somewhere before. A. saw B. have seen C. had seen D. see 14. Last night a tornado swept through Rockville. It everything in its path. A. destroyed B. was destroyed C. had destroyed D. has destroyed 15. When we the bill, we left the restaurant A. had paid B. were paying C. paid D. had been paid
mới học đến TOÁN 8 : HÌNH CHỮ NHẬT nên ko dùng kiến thức chưa học
giúp với ạ √3 sin4x +cos4x-4sin2x=1
6. My mother is a ………..woman. She always takes care of us. (care) 7. We often take part in English writing………………. at school. (compete) 8.The ………..of the internet was made in 20th century. (cover) 9. I shouted at the dog and it walked away …………….. . (oppoint) 10. He lost both his house and his ……… because of the storm. (live) Yêu cầu: +Phải nói được chỗ đó điền được từ gì +Phải giải thích vì sao chỗ đóa điền từ loại đó +Dịch luôn nhea (giống google quạo nhea)
B = - 2 + 4 + (- 6) + 8 + . . . + (- 18).
Giúp mình với mình đang cần gấp ạ cảm ơn nhìu
VI. Complete the sentence with the past simple or past perfect form of the verb in brackets. 1. They (live) in Paris for 10 years before they (move) home. 2. As soon as I (download) the document, I knew I (make)a mistake. 3. Mary (ring) John’s doorbell at 8:15 yesterday but John (already/ leave) the house. 4. By the time the firemen (arrive), the fire (destroy)three houses. 5. Our economy (not stand) a chance of developing before thegovernment (adopt) the open-door policy. 6. When I last (speak) to her, she still (not finish)her assignment. 7. Nobody (come) to the meeting because Angela (forget)to tell them about it. 8. She (go) to Disneyland three times when she (be) a little girl. 9. After I (complete) the form, I (give) it to the secretary. 10. Sarah (drive) three hundred miles by the time she (arrive)in Tacoma.
mọi người giúp mình với còn bài cuối thôi ạ !!!
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