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2 năm trước
Trên mặt nước có hai nguồn A và B phát sóng kết hợp cùng pha với tần số f = 20 Hz, tốc độ truyền sóng v = 0,6 m/s. Xét hai điểm M và N trên mặt nước với MA = 22 cm, MB = 29,5 cm và NA = 18,7cm, NB=8,2cm. Số điểm có biên độ dao động tổng hợp cực đại trên đoạn MN là:
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các bạn làm gấp giúp mình nhé! I. Choose the word whose underlined part is pronounced differently from that of the others in each group. 1.A. peaceful B. pleasure C. sleepy D. cheap 2.A. blossom B. chess C. messy D. passion 3.A. clothes B. fireworks C. scissors D. mountains 4.A. stadium B. place C. paddy D. lake 5.A. lunch B. music C. unpopular D. study II. Complete the sentences below using the correct form of comparative or superlative adjectives. Ex: - Lan is Hoa. (tall) Lan is taller than Hoa. - Nam is student in his class. (young) Nam is the youngest student in his class. 1. A new house is ……………………………… an old one. (expensive) 2. Motorbikes are ……………………………… bicycles. (fast) 3. My television is ……………………………… his television. (modern) 4. Summer is ……………………………… Spring. (hot) 5. Jane is ……………………………… her sister. (beautiful) 6. Skirts are ……………………………… dresses. (cheap) 7. Her English is ……………………………… my English. (good) 8. A bicycle is often ……………………………… a car in busy cities. (convenient) 9. Nile River is ……………………………… river in the world. (long) 10. This book is ……………………………… of these books. (interesting) 11. Ho Chi Minh City is ……………………………… city in Viet Nam. (big) 12. They are ……………………………… students in my class. (good) 13. These houses are ……………………………… in the village. (beautiful) 14. Winter is ……………………………… season in the year. (cold) 15. Airplane is ……………………………… means of transport. (fast) III. Give the correct form of the verbs in the simple future. 1. ……………………………… (they / come) tomorrow? 2. When ……………………………… (you / get) back? 3. If you lose your job, what……………………………… (you / do)? 4. They ……………………………… (do) it for you tomorrow. 5. My father ……………………………… (call) you in 5 minutes. 6. ……………………………… (she / get) the job, do you think? 7. We believe that she ……………………………… (recover) from her illness soon. 8. What ……………………………… (the weather / be) like tomorrow? 9. I promise I……………………………… (return) from school on time. 10. ( you / show )……………..me how to operate the new machine, please ? IV. Fill in the gap with should/ shouldn’t/ must/ mustn’t : 1.I don’t think you ………………………eat so much chocolate. It’s bad for your health. 2.I think waiters………………………………try to be pleasant with customers. 3.If you feel sick, you ……………………………… stay at home. It’s better for you. 4.I ……………………………… get my hair cut. I don’t like long hair. 5.We ………………………… go home. My mother has told me to arrive at ten o’clock. 6.I ……………………………… study hard. I want to pass the exam. 7.You ……………………………… accept things from strangers! 8.You ……………………………… steal things from shops. 9.Children ……………………………… eat junk food every day. 10. There is a ''No turn left'' sign. You ………………………..turn left. V.Fill in each blank with ONE appropriate word. 1.On the first day of Tet, people often go to ………………………to pray for a good new year. 2.If you visit England, you can go see Buckingham ……………………………………..…….. 3.I think that good health is……………………………………………..important than money. 4.I’m just going to the…………………………………… to buy some medicines and bandage. 5.You should put ……………… on your skin to protect it from the harmful effects of the sun. 6.Titov island in Ha Long Bay was named …………… a Russian cosmonaut, GhermannTitov. 7.The Sahara is the third…………….……………………………………….desert in the world. 8.Minh’s father is a farmer. He works on the ……………………….………………………… 9.Mary and I would like to ………………………….……………. English speaking club. 10.Lan can’t reach the book on the shelf……………………………………………..she is short. VI. Write the correct form or tense of the verbs in brackets. 1.Vietnamese people …………………..……….. (celebrate) Lunar New Year every year. 2.This Tet, my family ……………………………(not buy) Chung cakes. We will make them. 3.We usually ………….….(stay) at home on holiday, but this holiday we …………. (travel) abroad. 4.You shouldn’t ……………….………………….(wear) white clothes on the first day of Tet. 5.People spend a few days ……….……………………………(clean) their houses before Tet. 6.Tet …………………….…………………………..(occur) in late January or early February. 7.Miss Helen (help)…………………… us as soon as she (finish)...................................that letter. 8.Phong loves ………………………………………………...(eat) traditional food during Tet. 9.You must …….…………………………………….……(take) a boat ride around the island. 10.After …..…… (get) up, children get dressed in new clothes and say wishes to their parents.

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