2 phút trước

1 worked => work

2 go => going

3 carried => to carry

4 for => since

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Vài giây trước

1. worked => work

2. go => going

3. carried => to carry

4. for => since

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2 phút trước

Vì sao CO được coi là oxit còn H2O thì lại không ?

=>H2O  vẫn đc gọi là oxit trung tính chứ

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2 phút trước

vì H2O là chất có tính chất hóa học đặc biệt, hơn nữa nó là nước

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5 phút trước

Tách nhỏ ra bạn

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Bài 7:

$P=\dfrac{2x^2-6x+x^2+3x-3x^2-3}{\left(x-3\right)\left(x+3\right)}:\dfrac{2x-2-x+3}{x-3}$

$=\dfrac{-3\left(x+1\right)}{\left(x+3\right)}\cdot\dfrac{1}{x+1}=\dfrac{-3}{x+3}$

Bài 8:

$A=\dfrac{x^2+8x+8-x^2-4x-4}{x\left(x+2\right)}:\dfrac{x^2-x-3+x+2}{x\left(x+2\right)}$

$=\dfrac{4x+4}{x^2-1}=\dfrac{4}{x-1}$

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2 phút trước

$\dfrac{-3}{x+3}$

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2 phút trước

1. a few

2. a little

3. a few

4. many

5. a few

6. a little

7. a few

8. a few

9, many

10. little

11. a little

12. little

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7 phút trước

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.

Question 43: The ocean probably distinguishes the earth from other planets of the solar system, for scientists believe that large bodies of water are not existing on the other planets.

A. from                  B. probably                  C. for                  D. are not existing

Question 44: In many places in the world, social or religious restrictions which prevent women from travelling freely.

A. in                     B. religious                      C. which                      D. freely

Question 45: Halley’s comet, viewing through a telescope, was quite impressive.

A. viewing                 B. through                   C. quite                 D. impressive

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6 phút trước

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

A. Not many people bought our product because it was so bad.

B. Our product was of better quality so that more people would buy it.

C. Fewer people bought our product due to its bad quality.

Question 47: "How beautiful you are today!” he said.

A. He complimented her on being beautiful today.

B. He said to me that she was beautiful that day.

C. He complimented her on being beautiful that day.

D. He complemented her on being beautiful that day.

Question 48: The sooner we solve this problem, the better it will be for all concerned.

A. If all concerned are better, we can solve this problem soon.

B. If we could solve this problem soon, it would be better for all concerned.

C. If we can solve this problem soon, it will be better for all concerned.

D. It would be better for all concerned if we can solve this problem soon.

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5 phút trước

Question 43: The ocean probably distinguishes the earth from other planets of the solar system, for scientists believe that large bodies of water are not existing on the other planets.

A. from                  B. probably                  C. for                  D. are not existing

Question 44: In many places in the world, social or religious restrictions which prevent women from travelling freely.

A. in                     B. religious                      C. which                      D. freely

Question 45: Halley’s comet, viewing through a telescope, was quite impressive.

A. viewing                 B. through                   C. quite                 D. impressive

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.

A. Not many people bought our product because it was so bad.

B. Our product was of better quality so that more people would buy it.

C. Fewer people bought our product due to its bad quality.

Question 47: "How beautiful you are today!” he said.

A. He complimented her on being beautiful today.

B. He said to me that she was beautiful that day.

C. He complimented her on being beautiful that day.

D. He complemented her on being beautiful that day.

Question 48: The sooner we solve this problem, the better it will be for all concerned.

A. If all concerned are better, we can solve this problem soon.

B. If we could solve this problem soon, it would be better for all concerned.

C. If we can solve this problem soon, it will be better for all concerned.

D. It would be better for all concerned if we can solve this problem soon.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each of sentences in the following questions.

Question 49: Farmers depend on meteorologists. They need meteorologists' accurate forecasts for successful agricultural planning.

A. Due to meteorologists’ accurate forecasts, farmers depend on them for successful agricultural planning.

B. Farmers depend on meteorologists who need their accurate forecasts for successful agricultural planning.

C. Farmers need meteorologists’ accurate forecasts for successful agricultural planning and so they depend on you.

D. Farmers depend on meteorologists, whose accurate forecasts they need for successful agricultural planning.

Question 50: Their dog was very fierce. People didn’t dare to come up to their house.

A. If their dog were not fierce no one would visit their house.

B. Their dog was not fierce enough for people visit their house.

C. They had such a fierce dog so that people didn't dare to come up to their house.

D. They had so fierce a dog that no-one dared come up to their house

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8 phút trước

Gọi số mol CuO, Mg là a, b

=> 80a + 24b = 9,2

PTHH: CuO + 2HCl --> CuCl2 + H2O

a----->2a

Mg + 2HCl --> MgCl2 + H2

b----->2b

=> 2a + 2b = 0,3

=> a = 0,1; b = 0,05

=> $\left\{{}\begin{matrix}m_{CuO}=0,1.80=8\left(g\right)\\m_{Mg}=0,05.24=1,2\left(g\right)\end{matrix}\right.$

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7 phút trước

CuO+2HCl->CuCl2+H2O

x-------2x

Mg+2HCl->MgCl2+H2

y------2y

ta có hệ :

80x+24y=9,2

2x+2y=0,3

=>x=0,1 mol => m CuO=0,1.80=8g

=>y=0,05 mol=>m Mg=24.0,05=1,2g

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7 phút trước

mCuO=0,1.80=8(g)

mMg=0,05.24=1,2(g)

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