Cho tam giác ABC cân tại A. Trên cạnh BC lấy điểm D ( D khác B, C).
Trên tia đối của tia CB, lấy điểm E sao cho CE = BD. Đường vuông góc với BC kẻ từ D cắt
BA tại M. Đường vuông góc với BC kẻ từ E cắt tia AC tại N. MN cắt BC tại I.
1) Chứng minh rằng: DM = EN.
2) Chứng minh rằng IM = IN; BC < MN.
3) Gọi O là giao của đường phân giác góc A và đường thẳng vuông góc với MN tại I.
Chứng minh rằng:tg BMO =tgCNO . Từ đó suy ra điểm O cố định.

giúp mình với

I. Fill in each blank with the correct preposition.

1. I love to go shopping (in, on, at) Christmas time.

2. I live in the US (in, on, at) the 1980s.

3. I'll see you (at, in, on) a few weeks.

4. We like going to the movies (in, on, at) the evening.

5. He lives (in, to, at, x) New York.

6. She went (in, to, at, x) home.

7. I work (in, to, at, x) Seattle.

8. He went (in, at, to, x) his friend's house.

9. She arrived (in, at, to, x) London for the celebrations.

10. I am going to stay (in, at, to, x) home this weekend.

11. He works (in, at, to, x) the hospital.

12. I am going to see John (in, at, to, x) Florida this summer.

13. I arrived (in, at, to, x) work early this morning.

14. She came (in, at, to, x) home early.

15. We stayed (in, at, to, x) the grand Hotel.

16. They visited (in, at, to, x) Italy last summer.

17. She is going to travel (in, at, to, x) Greece this summer.

18. I will be (in, at, to, x) school later today.

19. He has been working (for, while, during) three weeks.

20. I fell asleep (during, for, while) the film.

21. Did you see Tom (for, while, during) your vacation?

22. We talked (for, while, during) an hour.

23. She watched TV (for, while, during) I cooked.

24. (For, While, During) our stay in London, we visited a lot of museums.

25. What did you do (for, while, during) you were in London.

26. I think I need to study French (for, while, during) a few months before I go there.

27. I came up with a great idea (for, while, during) I was thinking about my class.

28. They drove through the countryside (for, while, during) they were staying in France.

29. He was out of work (for, while, during) 6 months before he found a new job.

30. I broke my arm (for, while, during) I was playing squash.

31. Please, don't interrupt the teacher (for, while, during) she is speaking.

32. He broke into tears (for, while, during) the film.

33. Could you hold on (for, while, during) a few months?

34. I am just hopeless (about, at, by, for, from) playing the guitar.

35. She is furious (about, at, by, for, from) her son's grades in school.

36. I am upset (about, at, by, for, from) my health.

37. She was annoyed with tom (about, at, by, for, from) ignoring their agreement.

38. He gave her a cheek (for, in, of, to, with) a lot of money. for

39. The reason (for, in, of, to, with) this meeting is to discuss the merger. for

40. The decrease (for, in, of, to, with) profits is due to the bad market. In

41. There is a real demand (for, in, of, to, with) new products. for

42. We have seen a fall (for, in, of, to, with) prices recently. in

43. The cause (for, in, of, to, with) his problems is his family. of

44. Did you do any damage (for, in, of, to, with) the house? to

45. The difference (for, in, of, to, with, between) the two is very slight.

46. Are you doing anything special (in, on, at) New Year.

47. The plane is due to arrive (in, on, at) 19. 25.

48. Work is always more stress full (in, on, at) the end of the month.

49. We saw a ballet (in, on, at) Julia's birthday.

50. I was very tired (after, on, in, at) my trip to England.