I said to the man that I hadn't met him before.

Minh said that he had never come there before.

Susan told Jack that his sister had eaten too much chocolate.

Jane told Dat that she hadn't met him since that morning.

My dad said that he hadn't tried that restaurant yet.

1. had been -> were

2. doing -> to do

3. Unless -> If

4. had I known -> I had known

5. had knew -> had known

6. had finished -> finishes

7. more confident -> more confidently

8. would not be lost -> would not have been lost

9. would write -> would have written

10. would stop -> would have stopped

11. had you sent -> you had sent

12. will be sack -> will be sacked

13. will -> would

14. can help -> could help

15. will reduce -> reduce

"My favorite singer has just released a new album"

=>Noah said that his/her favorite singer had just released a new album.

"It hasn't rained much this year"

=>She said that it hadn't rained much that year.

"My dog has never swum in the sea"

=>Jane said her dog had never swum in the sea.

"I have never met your parents before"

=>Brian said he had never met my parents before.

1. My mom has not seen her for ten years

A. My mom has often seen her for the last ten years

B. About ten years ago, my mom used to meet her

C. The last time my mom saw her was ten years ago

D. My mom saw her ten years ago and will never meet her again

2. When will you start doing your exercise? Asked my father

A. My father asked me when would i start doing my exercise

B. My father asked me when i would start doing my exercise

C. My father asked me when i will start doing my exercise

D. My father asked me when will i start doing my exercise

3. They have not met Lisa for five years.

A. The last time they met Lisa was five years ago

B. It is three years when they will meet Lisa

C. They did not meet Lisa five years ago

D. During five years, they met Lisa once

4. This kind of food is a new experience for her.

A. She used to eat a lot of this kind of food

B. She is used to eating this kind of food

C. It is the first time she has eaten this kind of food

D. She has ever eaten this kind of food many times before

5. We have not spoken to Mark for years.

A. It has been a long time since we last spoke to Mark

B. Mark and we do not look the same age

C. Mark and we are friends for a long time

D. We often spoke to Mark years ago

\(A=3x^3y+6x^2y^2+3xy^3\\ A=3xy\left(x^2+2xy+y^2\right)\\ A=3xy\left(x+y\right)^2\\ \text{Với }x=\dfrac{1}{2};y=\dfrac{-1}{3},\text{ ta có }A=3\cdot\dfrac{1}{2}\cdot\dfrac{-1}{3}\left(\dfrac{1}{2}+\dfrac{-1}{3}\right)^2=\dfrac{-1}{72}\)

13A - 14B - 15C - 16D - 17B - 18B - 19C - 20A

Hóa chất sử dụng thêm: Quỳ tím.

Các bước làm:

- Trích mẫu thử.

- Thử tất cả dung dịch đã cho bằng quỳ tím. Nhận biết được Ba(OH)₂ vì làm quỳ hóa xanh, các dung dịch còn lại chia làm 2 phần:

+ Làm quỳ hóa đỏ: HCl, H₂SO₄, NH₄HSO₄

+ Không làm quỳ đổi màu: NaCl, BaCl₂

- Cho Ba(OH)₂ đã nhận biết vào các dung dịch thuộc nhóm làm quỳ hóa đỏ:

+ Tạo kết tủa trắng và khí có mùi khai: NH₄HSO₄

\(NH_4HSO_4+Ba\left(OH\right)_2\rightarrow BaSO_4+NH_3+2H_2O\)

+ Tạo kết tủa trắng, không có khí: H₂SO₄

\(H_2SO_4+Ba\left(OH\right)_2\rightarrow BaSO_4+2H_2O\)

+ Không hiện tượng: HCl

\(Ba\left(OH\right)_2+2HCl\rightarrow BaCl_2+2H_2O\)

- Dung dịch H₂SO₄ vừa nhận biết cho vào 2 dung dịch còn lại, tạo kết tủa với dung dịch nào thì dung dịch đó chứa BaCl₂. Còn lại là NaCl.

\(H_2SO_4+BaCl_2\rightarrow BaSO_4+2HCl\)

Look at the advice for a healthy lifestyle , and complete the sentences using more or less .

1. You have toothache . Eat ...less... candy

2. Get up early and do .....more.. exercise.

3. The examination is coming . Watch..less..Tv

4. Watch .....less..television and you can protect your eyes

5. You look tired , sleep....more.....

6. She should eat .less... fast food.

7. You are putting on weight. Eat..less..fast food

8. I will spend .less...time on computer games.

9. You have a cough. Drink ..more..warm water.

10. We should eat ...less.... junk food and eat.more... fruit and vegetables 

PHÂN số thập phân, không phải số thập phân!

If he hadn't spoken out about the economic problems, we wouldn't have become aware of them.