Hệ vật gồm 2 viên bị cùng khối lượng 1 kg chuyển động với vận tốc lần lượt bằng 3 m/s và 4m/s theo hai phương vuông góc với nhau. Tổng động lượng của hệ bằng

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I. Give the correct form of the verbs in brackets: 1. She already (watch) ……………………… this movie. 2. He (write) ……………………… his report yet? 3. We (travel) ……………………… to New York lately. 4. They (not give) ……………………… his decision yet. 5. Tracy (not see) ……………………… her friend for 2 years. 6. I (be) ……………………… to London three times. 7. It (rain) ……………………… since I stopped my work. 8. This is the second time I (meet) ……………………… him. 9. They (walk) ……………………… for more than 2 hours. 10. You (get) ……………………… married yet? II. Rewrite the sentences so that they are nearest in meaning to the sentence printed before them. 1. She started to live in Hanoi 2 years ago. (for) -> ………………………………………………… 2. He began to study English when he was young. (since) -> ………………………………………………… 3. I have never eaten this kind of food before. (This is) -> ………………………………………… 4. I have never seen such a beautiful girl before. (She is) -> ………………………………………… 5. This is the best novel I have ever read. (before) -> ………………………………………… III. Reorder the words to make sentences 1. Ha Noi/ homeless/ give/ in/ clothes/ away/ they/ warm/ to/ people. ................................................................................. 2. vacation/ since/ we/ haven’t/ last/ had/ a/ year. ................................................................................. 3. printer/ under/ this/ guarantee/ is. ................................................................................. 4. our/ a/ in/ makes/ volunteering/ difference/ community. ................................................................................. 5. you/ have/ finished/ homework/ your/ yet? .................................................................................