một vật nhỏ d đ đ h trên trục 0x với vận tốc có giá trị cực đại là vmax . Khi pha của vận tốc là pi/3 thì vận tốc có giá trị A.0,5vmax và đang giảm B. 0 và đang tăng C.0,5vmax và đang tăng D . (v max căn 3)/2 và đang giảm

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1. We are looking forward _____ you again soon. A. to see B. to seeing C. saw D. have seen 2. My mother was afraid to let the boy _____ the tree. A. to risk climbing B. to risk to climb C. risk climbing D. risk to climb 3. I remember _____ but he said I did not. A. to buy him a book B. buy him a book C. buying him a book D. to have bought him a book 4. Remember _____ john a present . today is his birthday. A. send B. to send C. sent D. sending 5. I suggest _____ some more mathematical puzzles. A. do B. to do C. doing D. done 6. Would you mind _____ the door? A. open B. to open C. opening D. opened 7. You should give up _____ or you will die of cancer. A. smoke B. to smoke C. smoking D. smoked 8. The driver stopped _____ a coffee because he felt sleepy. A. have B. to have C. having D. had 9. That old man tried to stop _____ because of his bad health. A. smoke B. smokes C. smoked D. smoking 10. There is nothing prevent us from______ the mystery of that palace. A. discover B. discovery C. discovering D. discoveries 11. Mr. Thomas does not allow people_____ in his office. A. smoke B. to smoke C. smoked D. smoking 12. We are not allowed _____ in that restricted area. A. to enter B. enter C. entering D. to entered 13. You had better _____ at home until you feel better. A. stay B. to stay C. staying D. stayed 14. The machine needs_____ . A. B & C are correct B. to be repaired C. repairing D. to repair 15. I couldn’t help _____ when I heard the story. A. laughing B. to laugh C. laughed D.laugh 16. She used that money _____ a new car. A.buy B. buying C. to buy D. for buying 17. Rex hotel was the best place for us _____. A. stays B. staying C. to stay D. stay 18. You can’t stop me from _____ what I want. A. doing B. do C. to do D. that I do 19. Peter usually help his mother ______. A. to do housework B. do housework C. with housework D.all are correct 20. I must go now. I promise _______ late. A. not being B. not to be C. to not be D. I won’t be 21. Can you manage_____ ______ the report in the morning? A. finishing / to write B. to finish / writing C. finishing / writing D. to finish / to write 22. Do you want ______ with you or do you want to go alone? A. me coming B. me to come C. that I will come D. that I come 23. I’m sure I locked the door. I clearly remember _____ it. A. locking B. to lock C. to have locked D. to be locked 24. She tried to be serious, but she couldn’t help ______. A. laughing B. to laugh C. that she laughed D. laugh 25. I like _____ the kitchen as often as possible. A. not cleaned B. clean C. to clean D. that I clean 26. He tried to avoid ______ my question. A. answering B. to answer C. answer D. how to answer 27. Could you please stop _______ so much noise? A. to make B. make C. making D. to have make 28. I enjoy ______ to music. A. listen B. to listen C. listening D. listened 29. Have you finished ______ your hair yet? A. wash B. washed C. washing D. to wash 30. If you walk into the road without looking, you risk _____ knocked down. A. been B. to be C. be D. being Mn ơi giải giúp em với