a) Chứng Minh: (2n + 3 )^2 - (2n - 3 )^2 luôn chia hết cho 24 b) Chứng Minh: (n + 5 )^2 - n^2 luôn chia hết cho 5

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EX 17. CHOOSE THE BEST OPTION: 1. Ann says that she isn’t ..........................in the life in the city. (interested , used, like, favorite) 2. Your sister looks..................today. (happy, happily, to be happy, at happy) 3. There are three ...................over there . (man, men, mans, mens) 4. Janet and I live quite far............ each other. (from, at , as , 0) 5. I’m a bit shy. I don’t ............... friends easily. (take, do , win , make ) 6. Which is your house? - The one............. (on right , on the right , at the right, on right hand) 7. Some scientists spend most of their lives.............. at rocks. (looking , look , to look , looked ) 8. People in Asia often drink ............... ( some tea, tea, the tea , many tea ) 9. The public library in the city has ....... of books (thousand, thousands, a thousand, two thousands) 10. Uncle Nghia sends poscards......... Ba from the cities he visits (at, to, for, from ) 11. Ba has a lot of history books. He will ............Liz some. (lend, borrow, give, get ) 12. He talked a lot.......................you (about, of, on, for) EX 18. Circle the best answer A, B, C or D: 1. My father wants to buy some stamps. Let’s go to the . A. supermarket B. factory C. Bookshop D. post office 2. Mrs. Linh wants some . Let’s go to the supermarket. A. clothes B. bread C. books D. All are correct 2. Peters wants to see some animals. Let’s go to the . A. bookshop B. library C. circus D. post office 4. Excuse me. - ? A . Thanks B. No C. Yes D. What 5. My mother lunch at 12.30. A. have B. has C. does D. plays 6. What time your father have dinner? - At 7.00 p.m. A. do B. does C. don’t D. doesn’t 7. Miss Linda works in a factory. He is a . A. worker B. teacher C. doctor D. student 8. She teaches English at Thang Long Primary School. She is a . A. worker B. student C. doctor D. teacher 9. They work in a hospital. They are . A. workers B. engineers C. students D. doctors 10. Do you beef? - Yes, we do. A. likes B. like C. to like D. not like EX 19. Circle the odd one out: 1. A. fish B. beef C. skirt D. chicken 2. A. coffee B. shoes C. cake D. water 3. A. want B. like C. Buy D. circus 4. A. pencil B. fruit C. pen D. eraser 5. A. apple B. postcard C. banana D. lemon 6. A. flower B. dress C. shorts D. shoes 7. A. buy B. send C. clothes D. see 8. A. bookshop B. T-shirt C. supermarket D. fashion shop

EX 15. Fill the gaps with correct words: I live in a (1).......................near the sea. It’s an old house, about (2)....................... years old, and it’s very small. There are two bedrooms upstairs but no (3)........................ The bathroom is downstairs (4)....................... to the kitchen and there’s a living room where there’s a lovely (5)....................... fireplace. There’s a garden in (6)....................of the house. The garden goes down to the beach and in spring (7)...................summer there are flowers everywhere. I (8)..................my house for many reasons: the (9).......................garden, the flowers in summer, the fire in winter. But the best thing is the view from my (10).......................bedroom window. EX 16. REARRANGE THESE WORDS: 1. like/ dinner/ house/ would/ have/ you/ to/ my/ at/tonight? …………………………………….. 2. watching/ prefers/ to/ books./ TV/ Hieu/ reading/ ……………………………………………… 3. kinds/ does/ like?/ what/ food/ Ha/ of/ …………………………………………………………. 4. is/ evening/ cartoon/ a/ there/ this/ ……………………………………………………………… 5. beef/ and/ Dung/ like/ does/ I/ so/. …………………………………………………………………. 6. work/ will/ do/ all/the/ machines/ for/ us/ ………………………………………………………….. 7. it/ hours/ about/ 2/ Thanh Hoa/ to/ takes/ by/ get/ to/ bus/. ->Thanh Hoa …………………………………………………………………………………………..