Giải bài toán bằng cách lập hệ phương trình: Hai thành phố A và B cách nhau 180km.Một xe ô tô khởi hành từ A về B,cùng một lúc mộtxe gắn máy khởi hành từ B đi ngược về A.Sau khi gặp nhau, xe ô tô phải đi thêm 2 giờ nữa mớitới B,còn xe gắn máy phải đi thêm 4 giờ 30 phút nữa mới tới A.Tìm vận tốc của mỗi xe

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Chỉ rõ thông tin ở đâu Have you ever noticed advertisements which say “Learn a foreign language in 6 weeks, or your money back”, “From the first day your pronunciation will be excellent. Just send ..."and so on. Of course, it never happens quite like that. The only language that is easy to learn is one’s mother tongue. And think how much practice that gets! In the past people usually learnt a foreign language in order to read the literature of the country. Now speaking the foreign language is what most people want. Every year many millions of people start learning one. How do they do it? Some people try at home, with books and records or tapes; some use radio, television programs, Some use computers and network; others go to evening classes. It is clearly easier to learn the language in the country where it is spoken. However most people cannot afford this and for many it is not necessary. 16. According to the advertisements if you cannot learn a foreign language in 6 weeks, you can _____ A. get your fee back B. have a free course C. continue to learn another 6-week course D. take another course 17. What language is the easiest to learn? A. foreign language B. any language C. second language D. first language 18. What did people use to learn a foreign language for? A. To talk with foreigners B. To find a better job C. To read the literature of the country D. To entertain 19. Which is NOT the way to learn a foreign language? A. Reading books B. Listening to tapes C. Talking on the phone D. Watching TV programs 20. The best way to learn a foreign language is to _________. A. read books B. go to evening classes C. spend a lot of money in learning D. live where the language is spoken