Một mẩu phấn được ném thẳng đứng lên cao với vận tốc 18km/h. Khi rời tay, mẩu phấn cách mặt đất 1,5m. Bỏ qua sức cản không khí. Chọn gốc thế năng tại mặt đất.Tính động năng , thế năng và cơ năng của viên phấn tại nơi ném.

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III. Use “should + verb” to make the sentences. Ex: I have a stomachache. (go to the doctor) → You should go to the doctor. 1. I feel very tired. (take a short rest) 2. Hoa has a bad cold. (stay in bed) 3. Minh’s room is very dirty, (clean it every day) 4. We’ll have an English test tomorrow. (learn your lessons carefully 5. Nga has a headache. (take an aspirin 6. My teeth aren’t strong and white. (brush them regularly) IV. Give the correct form of the verbs. 1. They ................. (do) it for you tomorrow. 2. My father................. (call) you in 5 minutes. 3. We believe that she ................. (recover) from her illness soon. 4. I promise I ................. (return) from school on time. 5. If it rains, he ................. (stay) at home. 6. You ................. (take) me to the zoo this weekend? 7. I think he ................ (not come) back his hometown. V. Using “should” or “shouldn’t” to make the correct sentences. Ex: - You shouldn’t study. (You/study) so hard. Have a holiday. - I enjoyed that play. We should go. (We/go) to the theatre more often. 1. ................. (You/park) here. It’s not allowed. 2. What ................. (I/cook) for breakfast this morning? 3. ................. (You/wear) a raincoat. It’s raining outside. 4. ................. (You/smoke). It’s bad for you. 5. ................. (We/arrive) at the airport two hours before the flight. 6. ................. (I/send) now or later? 7. Do you think ................. (I/apply) for this post? 8. What do you think................. (I/write) in this space on the form? 9. ................. (I/eat) any more cakes. I’ve already eaten too much. 10. This food is awful.................. (We/complain) to the manager. I. Fill in the blank with a suitable word. I think Tet holiday is the (1) ................... important celebration in Vietnam because it is an occasion for family-reunion, for human love and for better hope. All of (2) ................... seem to forget the hatred, bad lucks and then try to be nice (3) ................... others. Everyone is eager to take (4) ................... in many special activities, which are expected to bring (5) ................... lucks and success in the New Year. Tet is also the time for us to relax and enjoy our special foods, (6) ................... atmosphere (7) ................... a hard-working year. II. Frank is cooking. Give the useful advice using “you should” or “you shouldn’t” and notes in the box. Don’t leave the beef in the oven for more than one hour. Cut the onions as thin as possible. Use fresh herbs and fresh vegetables. Don’t put in too much salt and chilies. Wait until the water boils before you put the vegetables into it. Heat the oven before you put the beef in. Cut the beef into a lot of equal slices. 1. You shouldn’t leave the beef in the oven for more than one hour. 2. ................. the onions as thin as possible. 3. .................fresh herbs and fresh vegetables. 4. ................. in too much salt and chilies. 5. .................until the water boils before you put the vegetables into it. 6. ................. the oven before you put the beef in. 7. .................the beef into a lot of equal slices. I. Make the correct sentences using suggestions. 1. She/ hope/ that/ Mary/ come/ party/ tonight. 2. I/ finish/ my report/ 2 days. 3. If/ you / not/ study/ hard/,/ you/ not/ pass/ final/ exam. 4. You/ look/ tired,/ so/1/ bring/ you/ something/ eat. 5. you/ please/ give/ me/ lift/ station? II. Make questions with the underlined words. 1. Our school year starts on September 5th. 2. Summer vacation lasts for three months. 3. The longest vacation is summer vacation. 4. I usually visit my grandparents during my vacation. 5. My mother works eight hours a day. 6. Mr. Robinson is an English teacher.