Cho tam giác ABC cân tại A, CH là đường cao(H thuộc AB). Gọi D là điểm đối xứng với B qua A. a)Chứng minh tam giác DCB là tam giác vuông b) Chứng minh: góc DCA= góc HCB

Bài 1.     Cho tam giác ABC và H là trực tâm. Gọi M, N, P lần lượt là trung điểm của các cạnh AB, BC và CA; D, E, F lần lượt là trung điểm các đoạn HA, HB và HC.

            a) Chứng minh rằng các tứ giác MNFD và MEFP là các hình chữ nhật.

            b) Để các đoạn MD, ME và DP bằng nhau thì tam giác ABC phải là tam giác gì?

47. He sat at her desk (write)________________ a letter
48. He is accustomed to (eat)_________ Chinese food
49. We must change our ways. We can’t go on (live) ____________like this.
50. After discussing the economy, the Minister went on (talk)_______ about foreign
policy.
51. He is just about (leave)___________
52. We can’t afford (live)___________ in the centre
53. He loves parties; he is always the first (come)______ and the last
(leave)__________
54.  I am interested in (give)___________ money by my mother.
55. I don't mean (buy)_____________ that house
56. He wore glasses (avoid) (be) _____________________recognized.
57. In those days, being a student meant (spend)______________ long hours in the
library
58. I watched the woman (come)________ out of the house and get into a car.
59. She heard the doorbell (ring)____________ and went to answer it.
60. I can hear people (talk)___________. They must be in the next room.
61. He is always (talk)___________ so much in the class

31. They recommend (walk)_________________ around the lake
32. They recommend me (walk)_________________ around the lake
33. They encourage us (do)_____________ the test
34. They encourage (do)______________ the test
35. He denied (have)________________ been there.
36. His plan is (keep)______________ the affair secret. 
37. It seems impossible (save)____________ money 

38. It’s time we (water)______________ the flowers in the garden
39. The guest had the porters (carry) _______________ their luggage upstairs.
40. We incidentally saw the plane (crash)_______________ into the mountain.
41. The man noticed his assistant (leave)_____________ work earlier than usual.
42. They stopped (look)__________ at the pictures.
43. They stopped (smoke) _____________ because it is bad for their
health.
44. The water in this glass is too hot (drink)_______________.
45. It’s high time we (go)_____________ to work
46. They speak slowly enough for me (understand)_______________.

17. She sometimes has difficulty (breath)____________.
18. It’s useless (cry)___________. You’d better figure out the solutions.
19. I had a good time (enjoy)_______________ my trip to Bali.
20. It’s just a waste of time (contact)__________ Jane. She’s lost her phone.
21. Did you have any trouble 'with' (translate)___________ the report?
22. They do not allow (smoke)________________ here
23. They do not allow us (smoke)________________ here
24. There’s no point (write)__________ to her. She will not reply.
25. They quit (learn) ________________ at school last Monday
26. Would you rather (have)________________ a tea or coffee?
27. Tommy would rather (go)__________________ skiing than fishing last weekend.
28.  I couldn't bear (see)________________ her like that.
29. The teacher allowed (talk)_______________as long as it was in English.
30. The teacher allowed us (talk)______________ as long as its was in English.

1. You should (avoid) (make)_____________ silly mistakes.
2. I don’t feel like (to study)___________________ English today
3. Isabel got Mike (to wash)___________________ her car
4. I am always busy _________________ (do) the house work
5. I can’t stand (listen) ________________ to his complaints any longer.
6. Does your jacket need________ (wash)? ~ No, but you need________(iron) it.
7. I don’t mind________(walk) home, but I’d rather__________(get) a taxi
8. I can’t bear (have) ______________so much responsibility
9. What is your father (like)______________?
10. I regret (inform) ______________ you that your application was rejected.
11. Mary keeps (talk)_____________ about her problems.
12. Ireland doesn’t allow (smoke) ______________in bars.
13. What do you look (like)____________?
14. It’s no use ___________________ over spilt milk. (cry)
15. It is worth (save)________________ some money
16. It’s no good (look)____________for it here. You lost it