1.  Hai người dự định cùng làm một công việc hết 4 giờ. Nhưng thực tế họ chỉ cùng làm 3 giờ, sau đó người thứ nhất đi làm việc khác, người thứ hai tiếp tục làm 3 giờ nữa thì hoàn thành công việc được giao. Hỏi mỗi người làm riêng thì sau bao nhiêu lâu hoàn thành công việc được giao?

Cho đường tròn tâm O,  đường kính AB = 2R. Đường trung trực của OA cắt (O) tại C, D và cắt OA tại E. Gọi K thuộc cung BC nhỏ của (O), AK cắt CE tại H.

     1. Chứng minh: Tứ giác BEHK nội tiếp.

     2. Chứng minh:  AC² = AH. AK và AC = R.

           3. Chứng minh: Tâm đường tròn ngoại tiếp tam giác CHK luôn thuộc một đường thẳng cố định khi K di chuyển trên cung BC nhỏ của (O).

1. I have a big test next week, so I can’t accompany you in this trip.
→ If ______________________________________________________________________
2. The weather was beautiful but we didn’t go on the picnic.
→ Despite __________________________________________________________________
3. Social media networks are an excellent tool. You can use them to promote your business.
→ Social media networks _______________________________________________________
4. Janet learned a few words of French when she was in Paris last year. (UP)
→ Janet ______________________________________________________________________
5. I’m learning English because I want to get a good job when I finish my studies. (SO THAT)
→ I’m _______________________________________________________________________

1. When are you going to pay back __________ I lent you?
A. a money B. the money C. money D. moneys
2. Yoshi and Takashi __________ on a business trip now.
A. is B. are C. am D. be
3. Should __________ do more to help themselves?
A. employed people B. an unemployed people C. the unemployed people D. unemployed people
4. The people who live in __________ are called the Dutch.
A. Netherlands B. Netherland C. the Netherlands D. a Netherlands
5. David learned to play the violin when he was at __________.
A. an university B. the university C. university D. a university
6. Columbus was one of __________ to cross the Atlantic.
A. the first people B. a first people C. an first people D. first people.
7. We went by train to __________ of England.
A. West B. a West C. the West D. the Wests
8. The Prime Minister will give __________ this afternoon.
A. the speech B. a speech C. speech D. an speech
9. I haven’t been to __________ theater before.
A. a open air B. open air C. the open air D. an open air
10. Most people think that __________ is an important part of life.
A. the good job B. good job C. good jobs D. a good job
11. I don’t believe that a third of __________ should be paid in tax.
A. the person’s income B. a person’s income C. person’s income D. person income
12. The number of loyal customers __________ on the rise thanks to the company’s effective advertising
campaign.
A. is B. are C. am D. be
13. I try to go jogging at least four times __________.
A. the week B. of the week C. a week D. of a week
14. People __________ always willing to switch to a better product.
A. is B. Are C. Be D. Am
15. Too much rubbish is being dumped in __________.
A. sea B. The sea C. A sea D. Some sea
16. __________ the Sales Manager away?
A. is B. Are C. Am D. Be
17. Learning foreign languages ________ important.
A. is B. are C. Was D. Has
18. Sally spent six months out of __________.
A. work B. A work C. The work D. Some work
19. Hann never watches TV because he __________ too busy.
A. does B. Is C. Isn’t D. Doesn’t
20. Why don’t we go to the park __________?
A. by the car B. with the car C. with car D. by car
21. The manager is away on a business __________ so I am in charge of the office now.
A. trip B. tour C. voyage D. visit
22. If you want to see historical places, it is a good idea to go on a guided __________.
A. voyage B. visit C. tour D. cruise
23. They spent two weeks at a fashionable ski __________ in Switzerland.
A. resort B. boarding C. region D. area
24. They met on board of a luxurious yacht during a __________ in the Caribbean.
A. tour B. voyage C. cruise D. trip
25. After changing trains three times we arrived at our __________ in the end.
A. destination B. departure C. package D. countries
26. If you have any excess __________, you must pay extra money.
A. furniture B. tool C. luggage D. facility
27. David __________ a seat on the evening flight to Ho Chi Minh City.
A. travelled B. paid C. booked D. made
28. They are going to spend their holiday __________ rural France.
A. relaxing B. exploring C. reserving D. searching
29. Cua Lo Beach is also famous for its beautiful islands such as Lan Chau and Song Ngu which protect it
from heavy storms and strong winds __________ from the East Sea.
A. to come B. to come in C. coming D. coming in
30. __________ popular with tourist of young people age because they travel with minimum luggage and on
a limited budget.
A. Backpack B. Backpacking C. Backpacker D. Go backpacking
31. We went out for __________ dinner last night. __________ restaurant we went to was excellent.
A. x/ a B. the/ the C. x/ the D. the/ a
32. Did __________ police find __________ person who stole your bicycle?
A. a/ a B. the/ the C. a/ the D. the/ a
33. I'm looking for _________ job. Did Mary get __________ job she applied for?
A. a/ the B. the/ a C. a/ a D. the/ the
34. We live in __________ big house in __________ middle of the village
A. a/ a B. a/ the C. the/ the D. the/ a
35. This morning I bought a newspaper and a magazine. __________ newspaper is in my bag but I don't
know where __________ magazine is.
A. a/ a B. a/ the C. the/ the D. the/ a
36. If I was in charge, I _________ things differently.
A. did B. would do C. will do D. doing
37. There seem to be _________ tourists around this year.
A. little B. less C. few D. fewer
38. The people _________ we met in France have sent us a card.
A. who B. x C. whom D. all A, B & C
39. _________ people I met there were very friendly.
A. the B. a C. an D. x
40. If he _________ his IT skills, he'd easily get a job.
A. improves B. improved C. will improve D. is improving
41. _________ horses are animals, but not _________ animals are horses.
A. All/ the B. The/ all C. A/ the D. All/ all
42. There's still _________ wine in the bottle.
A. few B. a few C. any D. some
43. She travels to all kinds of _________ locations all over the world.
A. exotic B. same C. similar D. far
44. It arrived while I was on _________.
A. absence B. Christmas C. New Year D. safari
45. The result will depend on a number of different _________.
A. aspects B. factors C. ideas D. thoughts
46. Unfortunately, my flight to Da Nang was _________ for one and a half hour.
A. delayed B. held up C. held on D. both A & B
47. Vietnam has a great number of tourist _________; therefore, it is a good destination for many travellers
worldwide.
A. attractive B. attractives C. attraction D. attractions
48. From London to Oxford and back is a _________ trip of over a hundred miles.
A. round B. return C. one way D. both A & B
4. If you want to book a package tour, you should contact the _________ which I introduced to you
previously.
A. travel agent B. travel agency C. agent travel D. agency travel
50. He had _________ two expeditions to Spain to study wild plants by the end of 2010.
A. taken B. made C. done D. gone

vật sáng AB cao 2cm đặt vuông góc với trục chính của một thấu kính hội tụ(A nằm trên trục chính). Biết OA=15cm; OF=f=10cm . a)Dựng ảnh của vật AB qua TK  b) Tính OA',A'B',BB'

Câu 3:

a, Đốt cháy 5,6 g chất hữu cơ A, thu được 13,2 g CO₂ và 3,6 g H₂O.  Lập CTPT của A biết tỉ khối của A so với khí nitơ bằng 2.

b, Đốt cháy 3 gam chất hữu cơ A, thu được 8,8 gam CO₂ và 5,4 gam H₂O. Tìm công thức phân tử của A.Biết tỉ khối hơi của A so với H₂ bằng 15