Một người đi xe máy trên đoạn đường ABC.Biết trên đoạn đường AB người đó đi với vận tốc 16km/h, trong thời gian t1 = 15 phút; trên đoạn đường BC người đó đi với vận tốc 24km/h, trong thời gian t2 = 25 phút.tính vận tốc trung bình của người đó trên đoạn đường ABC.

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Exercise 2: Fill in the suitable prepositions 1.Thanks ……….. your letter. 2.I’ll see my mom and dad …………….. their farm. 3.We have to work hard ……….home and…………….school 4.We’ll visit her ……….Christmas. 5.Are you tired …………..watching TV? 6.She often brings them …………… school. 7.He works ……….a factory. 8.We always go to Ha Long Bay ……….vacation. 9.Tell me more ………..your family. 10.Can you send me a photo ………..your family? 11.He goes ……….the city …………his wife. 12.It takes 18 hours to get ………Hanoi ……….coach. 13.We write ……….each other twice a week. 14.He is the president ………………….our club. 15.She spends most ………the time ………the couch ……front …….the TV. 16.What do you usually do ………….school? 17.Why don’t you come …………..? 18.They swap cards ……….their friends. 19.Will you play a game ……………..catch? 20.What do you do …………….. recess? 21.They usually have portable CD player …………….small earphones. 22.I’ll take part…………….your club. 23.They read or study ………….the same time. 24.We enjoy all ………………… our classes. 25.………….school we study many things. 26.…… history, we study past and present events…Vietnam and …the world. 27.…………..physics, we learn …………how things work. 28.She learns how to use a computer ………..her Computer Science class. 29.Newspapers are ……….the racks …………….the middle. 30.Math books are ……………..the shelves ………..the left. 31.The largest library is ………Washington D.C, the capital ……….the USA. 32.Those books ……….the back …………the libraries are ………English. 33.Now, come and look ……………the kitchen. 34.My uncle is …………..work now. 35.Can I see the rest ………the house? 36.She’ll have a party ………..her birthday.