bài 1 có 2 quả cầu A,B đã nhiễm điện đươc treo vào 1 sợi chỉ mảnh . Đưa thanh kim loại đã cọ xát với lụa lần lượt đến mỗi quả cầu thì thấy thanh kim loại đẩy quả cầu A và hút quả cầu B.Hỏi quả cầu A,B nhiễm điện gì? tại sao?

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Last week I went to an International Food Festival taking place in Hai Phong. Because the festival only (1)________place for one day, hundreds of people crowded into it. It was the biggest food festival I had ever seen. There (2)________thirty countries participating in the festival. They brought with them traditional food specialities which reflected their unique national (3)________. I was really impressed (4)________the Cobb salad. It is an American garden salad made form chopped salad greens, tomato, bacon, chicken breast, hard-boiled eggs, avocado, cheese, and red-wine vinaigrette. (5)________the salad requires quite a few ingredients, it is quick to make. The American chef at the festival (6)________me the way to make the salad and it took me only 15 minutes to complete. How amazing! The next day I made Cobb salad (7)________my mum for lunch, and she loved it right away. (8)________good dish is steak pie, a traditional British meat pie made from stewing steak and beef gravy, enclosed in a pastry shell. Unfortunately, I did not have (9)________ time to listen to the chef give instructions on how to make this dish. However, I tried it and it was brilliant. Next year (10)________there is another food festival, I will definitely join in. 1. A. ran B. took C. went D. found 2. A. are B. is C. was D. were 3. A. cooking B. food C. foods D. cuisine 4. A. by B. at C. in D. on 5. A. But B. Although C. Because D. So 6. A. said B. asked C. gave D. showed 7. A. for B. with C. together D. like 8. A. One B. Another C. Second D. Next 9. A. little B. many C. enough D. few 10. A. while B if C. as D. because