1. Where was your bike left?

2. By whom was the champion defeated?

3. What will be repaired this year?

4. How is crab soup cooked?

1. This dress had been ordered before I went to bed last night.

2. The dishes had not been washed by my brother.

3. An international letter-writing contest had been won by me.

4. Mary's exercise had been done by 5 p.m.         

5. The report had not been finished by the boys before going to school.

6. This film had been seen by them before I called.

7. After the wall had been painted, I went to a cinema.

8. After the television had been watched by Thomas, he studied.

9. Had the clothes been ironed by the girl by afternoon?

10. The teeth had been brushed by my little brother before he went to bed last night.

Địa phương em đang sống thuộc khu vực địa hình trung du.

Mô tả: Nằm giữa miền núi và đồng bằng, vùng đồi đỉnh tròn sườn thoải xếp cạnh nhau, có những dấu hiệu của đồng bằng và cả miền núi.

1. This bouquet of flowers has been bought in that shop by my mother.

2. Jane's wallet has been found.

3. The report has been finished by our team.

4. My exercise has been finished for two days.

5. This movie has never been seen by him before.

6. The news has been heard by us already.

7. The contract has been signed by the employee.

8. Five concert tickets have been bought by these boys.

9. Computer science has been studied by his brother since April.

10. My cat has been taken care of well by my parents.

11. These reports have been typed by us for 1 hour.

12. The thief has been found by the police yesterday.

1. Ice cream is eaten by her everyday.

2. A new notebook is bought by Tom on the way to school.

3. The table is set by them.

4. A photo is taken by me.

5. Blue skirts are worn by us.

6. The cooker is bought by him.

7. I am not helped by them.

8. The essay is not written by you.

9. Is the bank robbed by that man?

10. Are you picked up by your dad?

1. B   

2. C     

3. A     

4. B   

5. D     

6. B       

7. C     

8. A

9. A     

10. A   

11. B   

12. D   

13. A   

14. B   

15. D

Vì ... nên

Do... nên

Nhờ .... mà

Có 2Z + N = 40

=> N = 40 - 2Z

Vận dụng \(1\le\dfrac{N}{Z}\le1,5\)

\(\Leftrightarrow1\le\dfrac{40-2Z}{Z}\le1,5\)

=>\(\dfrac{40}{3,5}\le Z\le\dfrac{40}{3}\)

\(\Leftrightarrow11,4\le Z\le13,3\)

Nếu Z = 12 => N = 16 => A = 28

       Z = 13 => N = 14 => A = 27