Nhan Quan
Triệu Vân Vy
Vài giây trước

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Cậu_Chủ_Nhỏ ...!
2 phút trước

Màu xanh lam

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nguyễn công
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màu xanh lam

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lê đoàn song nghi

điền since/for.ago

32. I've been working……since……….I got up.
33. The kettle has been boiling…………….ten minutes

34. They have been living in Madrid ……………..1972.
35. He has been in prison……………… four years.
36. He has known about the fact …………….a long time.
37. Conditions have changed a lot ……………….we were children.
38. Our teacher has been very ill …………….the last month.
39. I haven't eaten anything …………….twenty-four hours.
40. In fact he is always very rude. We have been waiting for him …………..half an hour.
41. I haven't seen him for three years. It is because I haven't been there…………..I left school.
42. I have been trying to mend this old fashioned car……………… hours.
43. One of my friends has been teaching in Tokyo…………….. three years. I haven't met him since last year.
44. I haven't enjoyed myself…………….two weeks since I heard that my final exam grades were low.
45. I know that you have never seen a lion………. you were born. Then now I say that we can go to the zoo and see one.
46. The police have been looking for him for two weeks……….. he escaped from the prison.
47. He hasn't spoken to me even a word …………..the last meeting.
48. I haven't phoned him ……………a week.
49. He has been the principal of our high school ……………1988.
49. Dean has been learning Japanese ………..two years.

50. I have been waiting ………….4 o'clock.

51. Sue has only been waiting ……………..20 minutes.

52. Tim and Tina have been learning English …………six years.

53. Fred and Frida have been learning French …………………1998.

54. Joe and Josephine have been going out together ……….Valentine's Day.

55. I haven't been on holiday ………………….last July.

56. Mary has been saving her money ………….many years.

57. I haven't eaten anything …………….breakfast.

58. You have been watching TV …………hours.

59.  We have been living here ……………2 months.

60. What have you been doing _____ we last spoke?

61. What has changed in your life _____ you moved here?
62. I have been working full-time _____ several weeks now.
63. Donald hasn't wanted to talk to me _____ our argument.

64. Tony Swanson has been with the company _____ 25 years.
65. The little girl was hungry because she hadn’t eaten anything _____ a while.
66. Puerto Ricans have been migrating to the United States _____ over a century.
67. Human beings have sought to know the unimaginable _____ the beginning of time.
68. It is believed that everything in the universe has existed _____ the Big Bang 15 billion years ago.
69. Is there a family member who has a talent that has been in your family _____ several generations?

70. The weather is dry. It hasn't rained…………….a few weeks.
71. It's been raining…………….lunchtime.
72. Sarah has lived in Paris…………….1995.
73. Paul has lived in London…………….10 years.
74. I'm tired of waiting. We've been sitting here…………….an hour.
75. Kevin has been looking for a job…………….he left school.
76. I haven't been to a party …………….ages.

Hoang Yen Pham
Vài giây trước

2. Victoria used to have long hair.

3.Victoria didn't use to have many friend.

4.Victoria used to wear glasses.

5.Victoris didn't used to go joging every morning

6. Victoria didn't used to live in the countyside

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nguyễn công
7 phút trước

gió mùa Đông Bắc, gió mùa Tây Nam, gió tây nam, Tín phong bán cầu Bắc.

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Triệu Vân Vy
7 phút trước
Tham khảo Nước ta nằm trong vùng nội chí tuyến Bắc bán cầu nên có gió Tín phong hoạt động quanh năm. Gió mùa Tây Nam và gió phơn Tây Nam chỉ hoạt động vào mùa hạ (tháng V đến tháng X) và gió mùa Đông Bắc chỉ hoạt động vào các tháng mùa đông (tháng XI đến tháng IV năm sau).   
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Tham khảo:

gió mùa Đông Bắc, gió mùa Tây Namgió tây nam, Tín phong bán cầu Bắc

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Vũ Đào Bảo 	Huy
8 phút trước

là công tác viên nha bạn

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CTV là công tác viên

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Cộng Tác Viên

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Nguyễn Quế Đức

True  or False

 

In the early 1900's, the world was developing at a very rapid pace, and with the growth of industrialization, cities became more crowded. Furthermore, with the invention automobiles, the traffic on the roads increased significantly, so there was a need for a better traffic system.

In 1912, an American policeman, Lester Wire, who was concerned with the increasing traffic, came up with the idea of the first electric traffic light. Based on Wire's design, the lights were first installed in Cleveland, Ohio, on August 5, 1914, at the corner of 105th and Euclid Avenue

The first electric traffic light had only red and green lights; it did not have a yellow light like modern- day traffic signals. Instead of a yellow light, it had a buzzer sound that was used to indicate that the signal would be changing soon.

In the year 1920, a policeman named William Potts in Detroit, Michigan invented the first four-way and three-coloured traffic lights. Apart from red and green, a third colour - amber (or yellow) - was introduced. Detroit became the first city to implement the four-way and three-colored traffic lights. In the 1920's, several automated traffic signals were installed in major cities around the world. The modern traffic light still uses this famous T-shaped model with three different colors.

A. Decide whether the following sentences are true (T) or false (F).

1. Due to the invention of cars, the traffic on the roads increased rapidly.

2. The first electric traffic light was invented in 1914 by Lester Wire.

3. The first electric traffic light had red, green and amber lights.

4. The yellow light didn’t exist until the 1920s.

5. Detroit was the first city to use the red, yellow, and green lights to control road traffic.

6. The modern traffic light works on the same principle as Wire’s original light.

Lazyboy
8 phút trước

1 T

2 T

3 F

4 T

5 T

6 F

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Khinh Yên
7 phút trước

T F F T T F

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Sang Ly
hnamyuh
6 phút trước

Câu 4 : 

Gọi $n_{NaCl} = a ; n_{KCl} = b$

Ta có : 58,5a + 74,5b = 20(1)$
$NaCl + AgNO_3 \to AgCl + NaNO_3$
$KCl + AgNO_3 \to AgCl + KNO_3$

Theo PTHH :

$m_{AgCl} = 143,5a + 143,5b = 40(2)$

Từ (1)(2) suy ra a = 0,0479 ; b = 0,0231$

$m_{NaCl}  = 0,0479.58,5 = 2,80125(gam)$
$m_{KCl} = 0,0231.74,5 = 1,72095(gam)$

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OH-YEAH^^
10 phút trước

Thái Bình Dương

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nguyễn công
10 phút trước

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Thái Bình Dương

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