Phân tử một hợp chất gồm 1 nguyên tử R liên kết với 2 nguyên tử O. Biết nguyên tố R chiếm 27,27% về khối lượng. a. Tính nguyên tử khối, cho biết KHHH và tên của nguyên tố R. b. Tính PTK của hợp chất.

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PART II. VOCABULARY Questions 6-20:choose the best answer 6. That's a_________ idea! A. greatly B. great C. big D. large 7. She can_________ four foreign languages. A. say B. tell C. speak D. talk 8. I love my family_________. A. very much B. very many C. very lots D. very a lot 9. I am a_________. I learn six days a week at school. A. teacher B. head master C. manager D. student 10.I_________a bike to school every day. A. go B. sail C. ride D. steer 11. Big C supermarket is always_________ with shoppers. A. crowding B. crowd C. crowded D. to crowd 12. If two people speak the same language, they usually have_________ attitudes and opinions. A similar B. similarity C. similarly D. different 13. There is so_________ on the road nowadays. A. many cars B. many bikes C. much traffic D. much motorbikes 14. I like_________ best because I enjoy working with numbers. A. literature B. maths C. biology D. geography 15._________ do you like learning best at school? A. How B. Whose C. What D. Who 16.._________does she want to learn English? - Because it's an international language. A. Where B. How C. What D. Why 17. Children have to_________ a lot of homework at home. A. make B. do C. answer D. explain 18. I am going to the_________ to borrow some books. A. bookshop B. lab C. computer room D. library 19. Would you like something to_____? - Yes, a glass of orange juice please. A. drink B. eat C. swallow D. have 20. What do you usually give your teachers on the _________ of Vietnamese teachers' day? A. time B. opportunity C. occasion D. chance