Một lò xo có chiều dài tự nhiên 20 cm. Khi kéo dãn lò xo để nó có chiều dài 22,5 cm thì lực đàn hồi của lò xo bằng 5 N. Hỏi phải kéo dãn lò xo có chiều dài bao nhiêu để lực đàn hồi của lò xo bằng 8 N?

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VII. Read the following text carefully and choose the correct answer A, B, C or D for each of the gap. When you are in Singapore, you can go around (1) ........................................... taxi, by bus, or by underground. I myself prefer the underground (2) ................... it is fast, easy and cheap. There are (3)......................buses and taxis in Singapore and one cannot drive along the road (4) ........................................ and without many stops, especially on the Monday morning. The underground is therefore usually quicker (5)....................taxis or buses. If you do not know Singapore very well, it is difficult (6).................the bus you want. You can take a taxi, but it is (7) ..................... expensive than the underground or a bus. On the underground, you find good maps that tell you the names of the stations and show you (8) ………………to get to them, so that it is easy to find your way. 1. A. at B. in C. by 2. A. but B. because C. when 3. A. many B. a lot C. few 4. A. quick B. quickly C. quicker 5. A. so B. like C. than 6. A. to find B. find C. finding 7. A. less B. more C. most 8. A. when B. how C. why II. Review the sentences. 1. There are more vehicles on the roads now. There did not ………………………………………………………………………………….… 2. I didn’t go to school because I was sick. I was sick, so ……………………………………………………………………………………. 3. It will be good if you eat less meat and more vegetables. You should ……………………………………………………………………………………… 4. What is the price of a plate of fried rice? How …………………………………………………………………………………………….. 5. Although English grammar is difficult, we like to study it. Despite…………………………………....……………………………………………………… 6. Although he is sick, he goes to school. In spite of ………………………………………………………………………………………. 7. What is the distance between Vinh and Ha Noi city? How……………………………………………………...……………………………………….?