Cho tam giác ABC góc A = 90o. Gọi E, G, F lần lượt là trung của AB, BC, AC. Từ E kẻ đường thẳng song song với BF, đường thẳng này cắt GF tại I. a)Tứ giác AEGF là hình gì ? b)Chứng minh tứ giác BEIF là hình bình hành c)Chứng minh tứ giác AGCI là hình thoi

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I. Give the correct forms of the verbs 13. Nga (not do) her homework yet. 14. Last year, I (visit) Hue with my family. 15. His uncle usually (play) sports in the afternoon. 16. Do you like (take) part in “Be a Buddy”? IV. Read and answer the questions We send young people of different nationalities on expeditions around the world. Our volunteers get the chance to work with local people to learn about different cultures.There are ten expeditions every year. Each expedition lasts for ten weeks and takes 150 volunteers. They go to countries such as Chile, Namibia, Mongolia and Viet Nam. Some of our volunteers work with local people to provide important facilities, for example, building schools. Others work in national parks or help scientists to do environmental research. These adventurous, young people come from all over the world. To become a volunteer, have to be between 17 and 25; you have to speak some English and you also have to be enthusiastic, flexible and hard – working members of a team. 17. Do young people of different nationalities go on expeditions around the world? _________________________________________________________________________________________ 18. How long does each expedition last? ________________________________________________________________________________________________ 19. What do the volunteers help the scientists? ________________________________________________________________________________________________ 20. Which language must we know to become a volunteer? ________________________________________________________________________________________________