Trên các cạnh SA, SB, SC của hình chóp SABC lần lượt lấy các điểm A',B',C' sao cho 3SA'=2SA, 7SB'=6SB, SC'=kSC. Tìm k để thể tích khối đa diện ABC.A'B'C' gấp 4 lần thể tích khối tứ diện SA'B'C' Helppppppp

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21. a. second name b.nick name c. middle name d. family name 22. a. age b.ages c.old d. ago 23. a. is b.are c. was d. were 24. a. in b. at c. on d.of 25. a. favorite b. interesting c. pleased d.best 26. a. photo b. photograph c. book d.a&b are correct V. Read the following passage and choose the item (a, b, c, or d) that best answers each of the questions about it. My best friend’s full name is Stuart Kenneth Young. His family, call him Ken, for short, but his nickname at school is ‘Sky’! He was born in Manchester, but now he lives in Newcastle. Sky is fifteen years old. He is 1.65m tall and he weighs 50 kilos. He’s got short brown hair and dark brown eyes. He is interested in all kinds of sport and music. His favorite group is U2, but his favorite singer is Bryan Adams. Sports View is his favorite TV program Sky’s favorite food is pizza. He hates people who smoke all the time. I like Sky because he’s got a good sense of humor. I also like him because he’s a great dancer. 27. Who is Stuart Kenneth Young? a. my best friend b. the author’s best friend c. Sky’s classmate d. Sky’s next-door neighbor 28. Where does he live? a. In Newcastle b. In manchester c. In the United State d. a & b 29. Stuart likes____________ a. all kinds of sport and music b. U2 c. Bryan Adams d. all are correct 30. Stuart is good at________ . a. music b. sport c dancing d. all are correct 31. Which of the following is not true? a. Stuart is fifteen years old. b. Stuart’s eyes are dark brown. c. Stuart likes pizza and people who smoke all the time. d. Stuart has a good sense of humor.